Pivotal bone anchor assembly with snap on articulating retainer

ABSTRACT

A polyaxial bone screw assembly includes a threaded shank body having an integral upper portion receivable in a receiver, the receiver having an upper channel for receiving a longitudinal connecting member and a lower cavity cooperating with a lower opening. The shank upper portion expands a retaining member in the receiver cavity to capture the shank upper portion in the receiver. The retaining member and attached shank are pivotable with respect to the receiver until locked in place with respect to the receiver. A pre-assembled receiver, retaining member and compression insert may be popped-on or snapped-on to the shank upper portion prior to or after implantation of the shank into a vertebra.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/456,163 filed Nov. 2, 2010 that is incorporatedby reference herein. This application is also a continuation-in-part ofU.S. patent application Ser. No. 12/924,802 filed Oct. 5, 2010 thatclaims the benefit of the following U.S. Provisional Patent ApplicationSerial Nos. 61/278,240, filed Oct. 5, 2009; 61/336,911, filed Jan. 28,2010; 61/343,737 filed May 3, 2010; 61/395,564 filed May 14, 2010;61/395,752 filed May 17, 2010; 61/396,390 filed May 26, 2010; 61/398,807filed Jul. 1, 2010; 61/400,504 filed July 28, 2010; 61/402,959 filedSep. 8, 2010; 61/403,696 filed Sep. 20, 2010; and 61/403,915 filed Sep.23, 2010, all of which are incorporated by reference herein. Thisapplication is also a continuation-in-part of U.S. patent applicationSer. No. 12/802,849 filed Jun. 15, 2010 that claims the benefit of U.S.Provisional Patent Application Ser. No. 61/268,708 filed Jun. 15, 2009,both of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

The present invention is directed to polyaxial bone screws for use inbone surgery, particularly spinal surgery and particularly to suchscrews with compression or pressure inserts.

Bone screws are utilized in many types of spinal surgery in order tosecure various implants to vertebrae along the spinal column for thepurpose of stabilizing and/or adjusting spinal alignment. Although bothclosed-ended and open-ended bone screws are known, open-ended screws areparticularly well suited for connections to rods and connector arms,because such rods or arms do not need to be passed through a closedbore, but rather can be laid or urged into an open channel within areceiver or head of such a screw.

Typical open-ended bone screws include a threaded shank with a pair ofparallel projecting branches or arms which form a yoke with a U-shapedslot or channel to receive a rod. Hooks and other types of connectors,as are used in spinal fixation techniques, may also include open endsfor receiving rods or portions of other structure.

A common mechanism for providing vertebral support is to implant bonescrews into certain bones which then in turn support a longitudinalstructure such as a rod, or are supported by such a rod. Bone screws ofthis type may have a fixed head or receiver relative to a shank thereof.In the fixed bone screws, the rod receiver head cannot be moved relativeto the shank and the rod must be favorably positioned in order for it tobe placed within the receiver head. This is sometimes very difficult orimpossible to do. Therefore, polyaxial bone screws are commonlypreferred.

Open-ended polyaxial bone screws allow rotation of the head or receiverabout the shank until a desired rotational position of the head isachieved relative to the shank. Thereafter, a rod or other longitudinalconnecting member can be inserted into the head or receiver andeventually the receiver is locked or fixed in a particular positionrelative to the shank. During the rod implantation process it isdesirable to utilize bone screws or other bone anchors that havecomponents that remain within the bone screw and further remain properlyaligned during what is sometimes a very lengthy, difficult procedure.

SUMMARY OF THE INVENTION

A polyaxial bone screw assembly according to the invention includes ashank having an upper portion and a body for fixation to a bone; areceiver defining an upper open channel, a cavity and a lower opening; acompression insert; and an open ring-like resilient retainer forcapturing the shank upper portion in the receiver along a cylindrical,frusto-conical, curvate or combination interface, the upper portion andattached retainer thereafter being pivotable with respect to thereceiver prior to locking of the shank into a desired configuration. Thecompression insert operatively engages the shank upper portion and maybe configured to be spaced from the retainer at all angular orientationsof the shank with respect to the receiver. According to an aspect of theinvention, an outer radius of the shank upper portion is different thanan outer radius of the retainer. In some embodiments, the shank andretainer have the same outer radius. In various embodiments of theinvention, the compression insert and retainer may or may not be down-or top-loaded through the upper open channel of the receiver while theshank upper portion is always bottom- or up-loadable into the receiverlower cavity at the lower opening. The resilient retainer is sized andshaped to expand about the shank upper portion and then “snap” or “pop”into place about the upper portion within the receiver cavity.Illustrated receivers typically include structure prohibiting thecompression insert from moving upwardly out of the receiver channel andthe compression insert prohibits movement of the retainer out of thereceiver. Thus, after the compression insert and retainer are loadedinto the receiver, both the compression insert and the retainer arecaptured within the receiver. A pre-assembled receiver, compressioninsert and retainer may be “popped on” or “snapped-on” to the shankupper portion prior to or after implantation of the shank into avertebra. Such a “popping on” procedure includes the steps of uploadingthe shank upper portion into the receiver lower opening, the shank upperportion pressing against and expanding the resilient retainer followedby contraction of the retainer to an original or near original shapethereof about the shank upper portion along a cylindrical, curvate orfrusto-conical surface thereof.

It is an object of the present invention to provide apparatus andmethods directed to polyaxial bone screw assemblies with features thatmay be readily, securely fastened to each other and to bone.Furthermore, it is an object of the invention to provide apparatus andmethods that are easy to use and especially adapted for the intended usethereof and wherein the tools are comparatively inexpensive to produce.Other objects and advantages of this invention will become apparent fromthe following description taken in conjunction with the accompanyingdrawings wherein are set forth, by way of illustration and example,certain embodiments of this invention.

The drawings constitute a part of this specification and includeexemplary embodiments of the present invention and illustrate variousobjects and features thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a polyaxial bone screwassembly according to the present invention including a shank, areceiver, an open retainer and a compression insert and also shown witha closure top and a longitudinal connecting member in the form of a hardrod.

FIG. 2 is an enlarged top plan view of the shank of FIG. 1.

FIG. 3 is a cross-sectional view taken along the line 3-3 of FIG. 2.

FIG. 4 is an enlarged side elevational view of the receiver of FIG. 1with portions broken away to show the detail thereof.

FIG. 5 is an enlarged side elevational view of the retainer of FIG. 1.

FIG. 6 is a top plan view of the retainer of FIG. 5.

FIG. 7 is a bottom plan view of the retainer of FIG. 5.

FIG. 8 is an enlarged front elevational view of the receiver of FIG. 1with portions broken away to show the detail thereof and shown in anearly stage of assembly with the retainer of FIG. 5.

FIG. 9 is a top plan view of the receiver and retainer of FIG. 8.

FIG. 10 is a front elevational view of the receiver, similar to FIG. 8,with portions broken away to show the detail thereof, further showingthe retainer and also the compression insert of FIG. 1 in a later stageof assembly, the compression insert shown in side elevation.

FIG. 11 is a perspective view, showing the receiver and compressioninsert of FIG. 10 in an assembled configuration.

FIG. 12 is an enlarged side elevational view with portions broken awayto show the detail thereof, showing the receiver, retainer andcompression insert of FIG. 11.

FIG. 13 is an enlarged and partial, partially exploded front elevationalview of the shank of FIG. 1 and the receiver, retainer and compressioninsert as assembled as in FIG. 12, with portions broken away to show thedetail thereof, the shank being shown implanted in a vertebra.

FIG. 14 is a partial front elevational view, similar to FIG. 13, withportions broken away to show the detail thereof and showing the shank ina stage of assembly with the retainer.

FIG. 15 is a partial front elevational view, similar to FIG. 14, withportions broken away to show the detail thereof and showing the shank ina subsequent stage of assembly with the retainer.

FIG. 16 is an enlarged and partial front elevational view, similar toFIG. 15, with portions broken away to show the detail thereof, showingthe shank fully assembled with the retainer and showing the compressioninsert in a subsequent rod receiving position.

FIG. 17 is an enlarged and partially exploded side elevational view ofthe shank, retainer, receiver, compression insert, rod and closure ofFIG. 1 with portions broken away to show the detail thereof, shown in astage of assembly subsequent to that shown in FIG. 16 and with the shankdisposed at an angle with respect to the receiver.

FIG. 18 is a reduced and partial perspective view of the assembly ofFIG. 17, shown fully assembled.

FIG. 19 is an enlarged and partial front elevational view of theassembly of FIG. 17 shown with the shank shown axially aligned with thereceiver.

FIG. 20 is an enlarged and partial cross-sectional view taken along theline 20-20 of FIG. 19.

FIG. 21 is an exploded perspective view of a second, alternativeembodiment of a polyaxial bone screw assembly according to the presentinvention including a shank, a receiver, a retainer, a compressioninsert and a closure top, and further shown with a longitudinalconnecting member in the form of a rod.

FIG. 22 is an enlarged side elevational view of the receiver of FIG. 21.

FIG. 23 is an enlarged perspective view of the compression insert ofFIG. 21.

FIG. 24 is a cross-sectional view of the receiver taken along the line24-24 of FIG. 22, with the compression insert of FIG. 21 shown in sideelevation in an early stage of assembly and further shown with theretainer of FIG. 21 with portions broken away to show the detailthereof.

FIG. 25 is an enlarged front elevational view of the receiver, retainerand compression insert of FIG. 24 with portions broken away to show thedetail thereof, the insert shown in a further stage of assembly.

FIG. 26 is a partial front elevational view of the shank, receiver,retainer and compression insert of FIG. 25 with portions broken away toshow the detail thereof and shown in a stage of assembly of the shankwith the retainer.

FIG. 27 is a partial front elevational view with portions broken away,similar to FIG. 26, showing the shank, retainer and compression insertfully assembled within the receiver and positioned for receiving the rodof FIG. 21.

FIG. 28 is an enlarged and partial side elevational view of the shank,receiver, retainer, compression insert, rod and closure of FIG. 21 withportions broken away to show the detail thereof and shown fullyassembled and with the shank disposed at an angle with respect to thereceiver.

FIG. 29 is an enlarged and partial cross-sectional view taken along theline 29-29 of FIG. 28.

FIG. 30 is an exploded perspective view of a third, alternativeembodiment of a polyaxial bone screw assembly according to the presentinvention including a shank, a receiver, a retainer, a compressioninsert and a closure top, and further shown with a longitudinalconnecting member in the form of a deformable rod.

FIG. 31 is an enlarged perspective view of the receiver of FIG. 30.

FIG. 32 is an enlarged perspective view of the compression insert ofFIG. 30.

FIG. 33 is an enlarged exploded perspective view of the receiver andcompression insert of FIG. 30 shown in a first stage of assembly.

FIG. 34 is a perspective view of the receiver and compression insert ofFIG. 33, shown assembled.

FIG. 35 is a cross-sectional view taken along the line 35-35 of FIG. 34.

FIG. 36 is an enlarged and partial front elevational view of the shank,receiver, retainer and compression insert of FIG. 30 with portionsbroken away to show the detail thereof and showing the shank in aninitial stage of assembly with the retainer.

FIG. 37 is an enlarged and partial and partially exploded frontelevational view of the shank, receiver, retainer, compression insert,rod and closure top of FIG. 30 with portions broken away to show thedetail thereof.

FIG. 38 is a partial front elevational view with portions broken away,similar to FIG. 37, showing all the components of FIG. 30 fullyassembled.

FIG. 39 is an enlarged and partial side elevational view of the assemblyshown in FIG. 30 with portions broken away to show the detail thereofand shown fully assembled as in FIG. 38 but with the shank disposed atan angle with respect to the receiver.

FIG. 40 is an exploded perspective view of a fourth, alternativeembodiment of a polyaxial bone screw assembly according to the presentinvention including a shank, a receiver, a retainer, a compressioninsert and a closure top, and further shown with a longitudinalconnecting member in the form of a rod.

FIG. 41 is an enlarged top plan view of the shank of FIG. 40.

FIG. 42 is a cross-sectional view taken along the line 42-42 of FIG. 41.

FIG. 43 is an enlarged top plan view of the retainer of FIG. 40.

FIG. 44 is an enlarged and partial side elevational view of the assemblyof FIG. 40 with portions broken away to show the detail thereof.

FIG. 45 is a reduced and partial cross-sectional view taken along theline 45-45 of FIG. 44.

FIG. 46 is a reduced side elevational view of the assembly of FIG. 40shown with the shank disposed at an angle with respect to the receiver.

FIG. 47 is an enlarged and partial side elevational view, similar toFIG. 46, with portions broken away to show the detail thereof.

FIG. 48 is an exploded perspective view of a fifth, alternativeembodiment of a polyaxial bone screw assembly according to the presentinvention including a shank, a receiver, a retainer, a compressioninsert and a closure top, and further shown with a longitudinalconnecting member in the form of a rod.

FIG. 49 is an enlarged and partial front elevational view of theassembly of FIG. 48 with portions broken away to show the detailthereof.

FIG. 50 is a side elevational view of the assembly of FIG. 48 shown withthe shank disposed at an angle with respect to the receiver.

FIG. 51 is an enlarged and partial side elevational view, similar toFIG. 50, with portions broken away to show the detail thereof.

FIG. 52 is an exploded perspective view of a sixth, alternativeembodiment of a polyaxial bone screw assembly according to the presentinvention including a shank, a receiver, a retainer, a compressioninsert and a closure top, and further shown with a longitudinalconnecting member in the form of a deformable rod.

FIG. 53 is an enlarged and partial front elevational view of theassembly of FIG. 52 with portions broken away to show the detailthereof.

FIG. 54 is an enlarged and partial cross-sectional view taken along theline 54-54 of FIG. 53.

FIG. 55 is a perspective view of an alternative retainer for use withpolyaxial bone screw assembles according to the invention.

FIG. 56 is a bottom perspective view of the retainer of FIG. 55.

FIG. 57 is a top plan view of the retainer of FIG. 55.

FIG. 58 is a bottom plan view of the retainer of FIG. 55.

FIG. 59 is an exploded perspective view of a seventh alternativeembodiment of a polyaxial bone screw assembly according to the presentinvention including a shank, a receiver, a retainer, a compressioninsert and a closure top, and further shown with a longitudinalconnecting member in the form of a rod.

FIG. 60 is an enlarged and partial front elevational view of theassembly of FIG. 59 with portions broken away to show the detailthereof.

FIG. 61 is an exploded perspective view of a eighth alternativeembodiment of a polyaxial bone screw assembly according to the presentinvention including a shank, a receiver, a retainer, a compressioninsert and a closure top, and further shown with a longitudinalconnecting member in the form of a rod.

FIG. 62 is an enlarged and partial front elevational view of theassembly of FIG. 61 with portions broken away to show the detailthereof.

FIG. 63 is an exploded perspective view of a ninth alternativeembodiment of a polyaxial bone screw assembly according to the presentinvention including a shank, a receiver, a retainer, a compressioninsert and a closure top, and further shown with a longitudinalconnecting member in the form of a rod.

FIG. 64 is an enlarged and partial front elevational view of theassembly of FIG. 63 with portions broken away to show the detailthereof.

FIG. 65 is an exploded perspective view of a tenth alternativeembodiment of a polyaxial bone screw assembly according to the presentinvention including a shank, a receiver, a retainer, a compressioninsert and a closure top, and further shown with a longitudinalconnecting member in the form of a rod.

FIG. 66 is an enlarged and partial front elevational view of theassembly of FIG. 65 with portions broken away to show the detailthereof.

FIG. 67 is an exploded perspective view of a eleventh alternativeembodiment of a polyaxial bone screw assembly according to the presentinvention including a shank, a receiver, a retainer, a compressioninsert and a closure top, and further shown with a longitudinalconnecting member in the form of a rod.

FIG. 68 is an enlarged and partial front elevational view of theassembly of FIG. 67 with portions broken away to show the detailthereof.

FIG. 69 is an exploded perspective view of a twelfth alternativeembodiment of a polyaxial bone screw assembly according to the presentinvention including a shank, a receiver, a retainer, a compressioninsert and a closure top, and further shown with a longitudinalconnecting member in the form of a rod.

FIG. 70 is an enlarged and partial front elevational view of theassembly of FIG. 69 with portions broken away to show the detailthereof.

FIG. 71 is an exploded perspective view of a thirteenth alternativeembodiment of a polyaxial bone screw assembly according to the presentinvention including a shank, a receiver, a retainer, a compressioninsert and a closure top, and further shown with a longitudinalconnecting member in the form of a rod.

FIG. 72 is an enlarged and partial front elevational view of theassembly of FIG. 71 with portions broken away to show the detailthereof.

DETAILED DESCRIPTION OF THE INVENTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention, which may be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriately detailed structure. It is also noted that any reference tothe words top, bottom, up and down, and the like, in this applicationrefers to the alignment shown in the various drawings, as well as thenormal connotations applied to such devices, and is not intended torestrict positioning of the bone attachment structures in actual use.

With reference to FIGS. 1-20 the reference number 1 generally representsa polyaxial bone screw apparatus or assembly according to the presentinvention. The assembly 1 includes a shank 4, that further includes abody 6 integral with an upwardly extending upper portion or capturestructure 8; a receiver 10; a retaining structure or retainer 12 and acompression or pressure insert 14. The receiver 10, retainer 12 andcompression insert 14 are initially assembled and may be furtherassembled with the shank 4 either prior or subsequent to implantation ofthe shank body 6 into a vertebra 13, as will be described in greaterdetail below. FIG. 1 further shows a closure structure 18 of theinvention for capturing a longitudinal member, for example, a rod 21which in turn engages the compression insert 14 that presses against theshank upper portion 8 into fixed frictional contact with the retainer12, so as to capture, and fix the longitudinal connecting member 21within the receiver 10 and thus fix the member 21 relative to thevertebra 13. The illustrated rod 21 is hard, stiff, non-elastic andcylindrical, having an outer cylindrical surface 22. It is foreseen (andalso will be described with respect to other embodiments) that the rod21 may be elastic, deformable and/or of a different cross-sectionalgeometry. The receiver 10 and the shank 4 cooperate in such a mannerthat the receiver 10 and the shank 4 can be secured at any of aplurality of angles, articulations or rotational alignments relative toone another and within a selected range of angles both from side to sideand from front to rear, to enable flexible or articulated engagement ofthe receiver 10 with the shank 4 until both are locked or fixed relativeto each other near the end of an implantation procedure.

The shank 4, best illustrated in FIGS. 1-3, is elongate, with the shankbody 6 having a helically wound bone implantable thread 24 (single ordual lead thread form) extending from near a neck 26 located adjacent tothe upper portion or capture structure 8, to a tip 28 of the body 6 andextending radially outwardly therefrom. During use, the body 6 utilizingthe thread 24 for gripping and advancement is implanted into thevertebra 13 leading with the tip 28 and driven down into the vertebrawith an installation or driving tool (not shown), so as to be implantedin the vertebra to near the neck 26, as more fully described in theparagraphs below. The shank 4 has an elongate axis of rotation generallyidentified by the reference letter A.

The neck 26 extends axially upward from the shank body 6. The neck 26may be of the same or is typically of a slightly reduced radius ascompared to an adjacent upper end or top 32 of the body 6 where thethread 24 terminates. Further extending axially and outwardly from theneck 26 is the shank upper portion 8 that provides a connective orcapture apparatus disposed at a distance from the upper end 32 and thusat a distance from the vertebra 13 when the body 6 is implanted in suchvertebra.

The shank upper portion 8 is configured for a pivotable connectionbetween the shank 4 (with attached retainer 12) and the receiver 10prior to fixing of the shank 4 in a desired position with respect to thereceiver 10. The shank upper portion 8 has an outer, convex andsubstantially spherical lower surface 34 that extends outwardly andupwardly from the neck 26 and terminates at a substantially planar ledgeor shelf 36 that is annular and disposed perpendicular to the shank axisA. The spherical lower surface 34 has an outer radius that is the sameor substantially similar to an outer radius of the retainer 12 as willbe described in greater detail below, the surface 34 as well as theretainer 12 outer surface participating in the ball and socket jointformed by the shank 4 and attached retainer 12 within the partiallyspherical surface defining an inner cavity of the receiver 10. Extendingupwardly from the ledge 36 is a cylindrical surface 38, the surface 38having a radius that is smaller than the radius of the lower sphericalsurface 34. Extending outwardly from the cylindrical surface 38 isanother annular surface or upper ledge 40 that faces toward the ledge 36and is also substantially perpendicular to the axis A. As will bediscussed in greater detail below, the lower ledge 36, cylindricalsurface 38 and upper ledge 40 cooperate to capture and fix the resilientopen retainer 12 to the shank upper portion 8, prohibiting movement ofthe retainer 12 along the axis A once the retainer 12 is located betweenthe ledges 36 and 40. Extending upwardly from the upper ledge 40 is acylindrical surface 42 having a radius smaller than the radius of thespherical surface 34 but larger than the radius of the cylindricalsurface 38. Extending upwardly from the surface 42 is an upper partiallyspherical or domed surface 44. The spherical surface 44 has an outerradius configured for sliding cooperation and ultimate frictional matingwith a substantially spherical concave surface of the compression insert14 that has the same or substantially similar radius as the surface 44.The radius of the surface 44 is smaller than the radius of the lowerspherical surface 34. Located near or adjacent to the surface 44 is anannular top surface 46. In the illustrated embodiment bevel 47 extendsabout the spherical surface 44 and is located between the sphericalsurface 44 and the annular planar top surface 46.

A counter sunk substantially planar base or seating surface 49 partiallydefines an internal drive feature or imprint 50. The illustratedinternal drive feature 50 is an aperture formed in the top surface 46and has a hex shape designed to receive a hex tool (not shown) of anAllen wrench type, into the aperture for rotating and driving the bonescrew shank 4. It is foreseen that such an internal tool engagementstructure may take a variety of tool-engaging forms and may include oneor more apertures of various shapes, such as a pair of spaced apartapertures or a multi-lobular or star-shaped aperture, such as those soldunder the trademark TORX, or the like. The seat or base 49 of the drivefeature 50 is disposed perpendicular to the axis A with the drivefeature 50 otherwise being coaxial with the axis A. In operation, adriving tool is received in the internal drive feature 50, being seatedat the base 49 and engaging the six faces of the drive feature 50 forboth driving and rotating the shank body 6 into the vertebra 13, eitherbefore the shank 4 is attached to the receiver 10 as shown in FIG. 13 orafter the shank 4 is attached to the receiver 10, with the shank body 6being driven into the vertebra 13 with the driving tool extending intothe receiver 10.

The shank 4 shown in the drawings is cannulated, having a small centralbore 51 extending an entire length of the shank 4 along the axis A. Thebore 50 is defined by an inner cylindrical wall of the shank 4 and has acircular opening at the shank tip 28 and an upper opening communicatingwith the internal drive 50 at the surface 49. The bore 51 is coaxialwith the threaded body 6 and the upper portion 8. The bore 51 provides apassage through the shank 4 interior for a length of wire (not shown)inserted into the vertebra 13 prior to the insertion of the shank body6, the wire providing a guide for insertion of the shank body 6 into thevertebra 13.

To provide a biologically active interface with the bone, the threadedshank body 6 may be coated, perforated, made porous or otherwisetreated. The treatment may include, but is not limited to a plasma spraycoating or other type of coating of a metal or, for example, a calciumphosphate; or a roughening, perforation or indentation in the shanksurface, such as by sputtering, sand blasting or acid etching, thatallows for bony ingrowth or ongrowth. Certain metal coatings act as ascaffold for bone ingrowth. Bio-ceramic calcium phosphate coatingsinclude, but are not limited to: alpha-tri-calcium phosphate andbeta-tri-calcium phosphate (Ca₃(PO₄)₂, tetra-calcium phosphate(Ca₄P₂O₉), amorphous calcium phosphate and hydroxyapatite(Ca₁₀(PO₉)₆(OH)₂). Coating with hydroxyapatite, for example, isdesirable as hydroxyapatite is chemically similar to bone with respectto mineral content and has been identified as being bioactive and thusnot only supportive of bone ingrowth, but actively taking part in bonebonding.

With particular reference to FIGS. 1, 4 and 8-11, the receiver 10 has agenerally U-shaped appearance with a partially discontinuoussubstantially cylindrical inner profile and a partially cylindrical andpartially faceted outer profile. The receiver 10 has an axis of rotationB that is shown in FIG. 1 as being aligned with and the same as the axisof rotation A of the shank 4, such orientation being desirable, but notrequired during assembly of the receiver 10 with the shank 4. After thereceiver 10 is pivotally attached to the shank 4, either before or afterthe shank 4 is implanted in a vertebra 13, the axis B is typicallydisposed at an angle with respect to the axis A, as shown, for example,in FIGS. 17 and 18.

The receiver 10 includes a substantially cylindrical base 58 integralwith a pair of opposed upstanding arms 60 forming a cradle and defininga U-shaped channel 62 between the arms 60 with an upper opening,generally 63, and a U-shaped lower seat 64, the channel 62 having awidth for operably snugly receiving the rod 21 between the arms 60. Eachof the arms 60 has an interior surface 66 that has a cylindrical profileand further includes a partial helically wound guide and advancementstructure 68 extending radially inwardly from the surface 66 and locatedadjacent top surfaces 69 of each of the arms 60. In the illustratedembodiment, the guide and advancement structure 68 is a partialhelically wound interlocking flangeform configured to mate underrotation with a similar structure on the closure structure 18, asdescribed more fully below. However, it is foreseen that the guide andadvancement structure 68 could alternatively be a square-shaped thread,a buttress thread, a reverse angle thread or other thread-like ornon-thread-like helically wound discontinuous advancement structure foroperably guiding under rotation and advancing the closure structure 18downward between the arms 60, as well as eventual torquing when theclosure structure 18 abuts against the rod 21.

An opposed pair of tool receiving and engaging apertures 71 are formedon outer surfaces 72 of the arms 60. Furthermore, two additional pair oftool receiving and engaging apertures 73 are formed on the arm surfaces72 between each top surface 69 and the aperture 71. Some or all of theapertures 71 and 73 may be used for holding the receiver 10 duringassembly with the shank 4 and the retainer 12, during the implantationof the shank body 6 into a vertebra when the shank is pre-assembled withthe receiver 10, and during assembly of the bone anchor assembly 1 withthe rod 21 and the closure structure 18. It is foreseen that toolreceiving grooves or apertures may be configured in a variety of shapesand sizes and be disposed at other locations on the receiver arms 62. Asillustrated, the apertures 71 do not extend completely through the arms60. At each aperture 71, a thin wall 75 partially defines the aperture71, the wall 75 being pushed or crimped inwardly toward and into acooperating aperture of the pressure insert 14 during assembly therewithas will be described in greater detail below. Alternatively, and as willbe described in greater detail below, the receiver or the pressureinsert may be equipped with spring tabs that bias against a respectivepressure insert or receiver to prohibit rotational movement of theinsert about the receiver axis once the insert is loaded in the receiverand positioned with the rod-receiving channel of the insert in alignmentwith the U-shaped channel of the receiver.

Communicating with and located beneath the U-shaped channel 62 of thereceiver 10 at the base portion 58 thereof is a chamber or cavity,generally 76, defined in part by a lower inner cylindrical surface 78, asubstantially curved or spherical seating surface portion 80, a lowerledge 82, a central cylindrical portion 84, and an upper shelf,generally 86, further defined by a lower annular surface or stop 87, acylindrical surface 88 and an upper frusto-conical surface 89. Anannular surface 90 disposed perpendicular to the axis B spans betweenthe surface 89 and the cylindrical surface 66 that substantially defineseach of the receiver inner arms. In the illustrated embodiment, afrusto-conical or beveled surface 91 is located between the sphericalseating surface 80 and the lower ledge 82. Opposed grooves 92 are formedin the shelf 86, the grooves 92 located near each U-shaped lower seat64, the grooves 92 being sized and shaped for receiving the retainer 12there through during assembly of the retainer 12 with the receiver 10 aswill be described in greater detail below. The central cylindricalportion 84 is sized and shaped to allow for expansion of the retainer 12about the surface 42 of the shank upper portion 8 during assembly whilethe upper shelf 86 acts as a stop, prohibiting upward movement of theretainer 12 out of the receiver cavity 76. The seating surface 80 issized and shaped for slidably mating with the retainer 12 and also thesurface 34 of the shank 4 and ultimately frictionally mating with theretainer 12 and or the surface 34 as will be described in greater detailbelow. The lower cylindrical surface 78 includes a bottom edge or neck93 that forms a lower opening, generally 95, that communicates with boththe cavity 76 and a receiver lower exterior or bottom 94 of the base 58.The neck 93 is substantially coaxially aligned with respect to therotational axis B of the receiver 10. The lower neck 93 is also sizedand shaped to be smaller than an outer radial dimension of the retainer12 when the retainer 12 is fixed to the shank upper portion 8, so as toform a restriction to prevent the structure 12 and attached shankportion 8 from passing through the cavity 76 and out the lower exterior94 of the receiver 10 during operation thereof.

With particular reference to FIGS. 1 and 5-10, the open retainer 12 thatoperates to capture the shank upper portion 8 within the receiver 10 hasa central axis C that is operationally the same as the axis A associatedwith the shank 4 when the shank upper portion 8 and the retainer 12 areinstalled within the receiver 10. The retainer 12 is made from aresilient material, such as a stainless steel or titanium alloy, so thatthe retainer 12 may be expanded during assembly as will be described ingreater detail below. However, because there is no need to compress theretainer 12 during assembly, the opening or slit that allows forexpansion of the retainer 12 is designed to be very narrow,advantageously providing substantial or almost full surface contactbetween the retainer and the shank upper portion 8 and also between theretainer and the receiver seating surface 80. The retainer 12 has acentral channel or hollow through bore, generally 101, that passesentirely through the structure 12 from a top surface 102 to a bottomsurface 104 thereof. The bore 101 is primarily defined by adiscontinuous inner cylindrical surface 105 that runs from the topsurface 102 to the bottom surface 104. In some embodiments of theinvention, as will be described in greater detail below, notches orgrooves may be formed in the inner and/or bottom surfaces to more evenlydistribute stress across the entire retainer during expansion thereof.The retainer 12 further includes an outer substantially sphericalsurface 107 running between the top surface 102 and the bottom surface104, the surface 107 having the same or similar radius as the receiverseating surface 80 and the shank lower spherical surface 34. Theresilient retainer 12 further includes first and second end surfaces,109 and 110 disposed in spaced relation to one another when the retaineris in a neutral state. Both end surfaces 109 and 110 are disposedsubstantially perpendicular to the top surface 102 and the bottomsurface 104. The embodiment shown in FIGS. 1-20 illustrates the surfaces109 and 110 as substantially parallel, however, it is foreseen that itmay be desirable to orient the surfaces obliquely or at a slight angle.

With reference to FIGS. 1 and 10-16, the compression insert 14 isillustrated that is sized and shaped to be received by and down-loadedinto the receiver 10 through the channel 64 and then rotated (see arrowR) as best illustrated in FIGS. 10 and 11. The compression insert 14 hasan operational central axis that is the same as the central axis B ofthe receiver 10. With particular reference to FIG. 12, the compressioninsert 14 has a central channel or through bore substantially defined byan inner cylindrical surface 121 coaxial with an inner partiallyspherical surface 122. The compression insert 14 through bore is sizedand shaped to receive a driving tool (not shown) therethrough thatengages the shank drive feature 50 when the shank body 6 is driven intobone with the receiver 10 attached. The surface 122 is sized and shapedto slidingly receive and ultimately frictionally engage thesubstantially spherical or domed surface 44 of the shank upper portion 8such that the surface 44 initially slidingly and pivotally mates withthe spherical surface 122 to create a ball-and-socket type joint. Thesurfaces 44 and/or 122 may include a roughening or surface finish to aidin frictional contact between them once a desired angle of articulationof the shank 4 with respect to the receiver 10 is reached.

The compression insert 14 has a substantially cylindrical body 126integral with a pair of upstanding arms 127. The bore defined by theinner surface 121 is disposed primarily within and through the body 126and communicates with a generally U-shaped through channel 131 that isdefined by the upstanding arms 127. The channel 131 has a lower seat 132sized and shaped to closely, snugly engage the rod 21. It is foreseenthat an alternative embodiment may be configured to include planarholding surfaces that closely hold a square or rectangular bar as wellas hold a cylindrical rod-shaped, cord, or sleeved cord longitudinalconnecting member. The arms 127 disposed on either side of the channel131 extend upwardly from the body 126 to top surfaces 133. The arms 127are sized and configured for ultimate placement below the receiver guideand advancement structure 68. It is foreseen that in some embodiments ofthe invention, the arms may be extended and the closure top configuredsuch the arms ultimately directly engage the closure top 18 for lockingof the polyaxial mechanism, for example, when the rod 21 is made from adeformable material. In such embodiments, the insert 14 would include arotation blocking structure or feature that abuts against cooperatingstructure located on an inner wall of the receiver 10 (such as theinsert shown with the assembly shown in FIGS. 30-39, for example),preventing rotation of the insert with respect to the receiver when theclosure top is rotated into engagement with the insert. In the presentembodiment, the top surfaces 133 of the arms 127 are ultimatelypositioned in spaced relation with the closure top 18, so that theclosure top 18 frictionally engages the rod 21 only, pressing the rod 21downwardly against the seating surface 132, the insert 14 in turnpressing against the shank 4 upper portion 8 that presses against theretainer 12 to lock the polyaxial mechanism of the bone screw assembly 1at a desired angle.

The insert body 126 has a bottom surface 135 that is adjacent to theinner spherical surface 122. In the illustrated embodiment, the surface134 is disposed at an angle with respect to the cylindrical surface ofthe body 126, providing improved clearance between components of theassembly 1 (as shown, for example, in FIG. 12). In other embodiments,the bottom surface may be substantially perpendicular to the cylindricalbody 126 or have more than one curved, conical or annular surfaces.

The illustrated insert 14 further includes other features formanipulating and holding the insert 14 within the receiver 10. Eachinsert arm 127 includes an outer surface 137 having a substantiallyvertical groove 138 formed thereon, the grooves 138 cooperate with thereceiver crimp wall 75 to aid in alignment of the insert channel 131with the receiver channel 62.

The insert body 126 has an outer diameter slightly smaller than adiameter between crests of the guide and advancement structure 68 of thereceiver 10, allowing for top loading of the compression insert 14 intothe receiver opening 63, with the arms 127 of the insert 14 beinglocated between the receiver arms 60 during insertion of the insert 14into the receiver 10. Once the arms 127 of the insert 14 are generallylocated beneath the guide and advancement structure 68, the insert 14 isrotated into place about the receiver axis B (see FIG. 11 and the arrowR) until the insert top surfaces 133 are located directly below theguide and advancement structure 68 of each receiver arm 60 as will bedescribed in greater detail below.

With reference to FIGS. 1 and 17-20, the illustrated elongate rod orlongitudinal connecting member 21 (of which only a portion has beenshown) can be any of a variety of implants utilized in reconstructivespinal surgery, but is typically a cylindrical, elongate structurehaving the outer substantially smooth, cylindrical surface 22 of uniformdiameter. The rod 21 may be made from a variety of metals, metal alloysand deformable and less compressible plastics, including, but notlimited to rods made of elastomeric, polyetheretherketone (PEEK) andother types of materials, such as polycarbonate urethanes (PCU) andpolyethylenes.

Longitudinal connecting members for use with the assembly 1 may take avariety of shapes, including but not limited to rods or bars of oval,rectangular or other curved or polygonal cross-section. The shape of theinsert 14 may be modified so as to closely hold the particularlongitudinal connecting member used in the assembly 1. Some embodimentsof the assembly 1 may also be used with a tensioned cord. Such a cordmay be made from a variety of materials, including polyester or otherplastic fibers, strands or threads, such as polyethylene-terephthalate.Furthermore, the longitudinal connector may be a component of a longeroverall dynamic stabilization connecting member, with cylindrical orbar-shaped portions sized and shaped for being received by thecompression insert 14 of the receiver having a U-shaped, rectangular- orother-shaped channel, for closely receiving the longitudinal connectingmember. The longitudinal connecting member may be integral or otherwisefixed to a bendable or damping component that is sized and shaped to belocated between adjacent pairs of bone screw assemblies 1, for example.A damping component or bumper may be attached to the longitudinalconnecting member at one or both sides of the bone screw assembly 1. Arod or bar (or rod or bar component) of a longitudinal connecting membermay be made of a variety of materials ranging from deformable plasticsto hard metals, depending upon the desired application. Thus, bars androds of the invention may be made of materials including, but notlimited to metal and metal alloys including but not limited to stainlesssteel, titanium, titanium alloys and cobalt chrome; or other suitablematerials, including plastic polymers such as polyetheretherketone(PEEK), ultra-high-molecular weight-polyethylene (UHMWP), polyurethanesand composites, including composites containing carbon fiber, natural orsynthetic elastomers such as polyisoprene (natural rubber), andsynthetic polymers, copolymers, and thermoplastic elastomers, forexample, polyurethane elastomers such as polycarbonate-urethaneelastomers.

With reference to FIGS. 1 and 17-20, the closure structure or closuretop 18 shown with the assembly 1 is rotatably received between thespaced arms 60 of the receiver 10. It is noted that the closure 18 topcould be a twist-in or slide-in closure structure. The illustratedclosure structure 18 is substantially cylindrical and includes an outerhelically wound guide and advancement structure 182 in the form of aflange that operably joins with the guide and advancement structure 68disposed on the arms 60 of the receiver 10. The flange form utilized inaccordance with the present invention may take a variety of forms,including those described in Applicant's U.S. Pat. No. 6,726,689, whichis incorporated herein by reference. Although it is foreseen that theclosure structure guide and advancement structure could alternatively bea buttress thread, a square thread, a reverse angle thread or otherthread like or non-thread like helically wound advancement structure,for operably guiding under rotation and advancing the closure structure18 downward between the arms 60 and having such a nature as to resistsplaying of the arms 60 when the closure structure 18 is advanced intothe channel 62, the flange form illustrated herein as described morefully in Applicant's U.S. Pat. No. 6,726,689 is preferred as the addedstrength provided by such flange form beneficially cooperates with andcounters any reduction in strength caused by the any reduced profile ofthe receiver 10 that may more advantageously engage longitudinalconnecting member components. The illustrated closure structure 18 alsoincludes a top surface 184 with an internal drive 186 in the form of anaperture that is illustrated as a star-shaped internal drive such asthat sold under the trademark TORX, or may be, for example, a hex drive,or other internal drives such as slotted, tri-wing, spanner, two or moreapertures of various shapes, and the like. A driving tool (not shown)sized and shaped for engagement with the internal drive 186 is used forboth rotatable engagement and, if needed, disengagement of the closure18 from the receiver arms 60. It is also foreseen that the closurestructure 18 may alternatively include a break-off head designed toallow such a head to break from a base of the closure at a preselectedtorque, for example, 70 to 140 inch pounds. Such a closure structurewould also include a base having an internal drive to be used forclosure removal. A base or bottom surface 188 of the closure is planarand further includes a point 189 and a rim 190 for engagement andpenetration into the surface 22 of the rod 21 in certain embodiments ofthe invention. The closure top 18 may further include a cannulationthrough bore (not shown) extending along a central axis thereof andthrough the top and bottom surfaces thereof. Such a through boreprovides a passage through the closure 18 interior for a length of wire(not shown) inserted therein to provide a guide for insertion of theclosure top into the receiver arms 60.

Preferably, the receiver 10, the retainer 12 and the compression insert14 are assembled at a factory setting that includes tooling for holding,alignment and manipulation of the component pieces, as well as crimpinga portion of the receiver 10 toward the insert 14. In somecircumstances, the shank 4 is also assembled with the receiver 10, theretainer 12 and the compression insert 14 at the factory. In otherinstances, it is desirable to first implant the shank 4, followed byaddition of the pre-assembled receiver, retainer and compression insertat the insertion point (see, e.g., FIG. 13). In this way, the surgeonmay advantageously and more easily implant and manipulate the shanks 4,distract or compress the vertebrae with the shanks and work around theshank upper portions or heads without the cooperating receivers being inthe way. In other instances, it is desirable for the surgical staff topre-assemble a shank of a desired size and/or variety (e.g., surfacetreatment of roughening the upper portion 8 and/or hydroxyapatite on theshank 6), with the receiver, retainer and compression insert. Allowingthe surgeon to choose the appropriately sized or treated shank 4advantageously reduces inventory requirements, thus reducing overallcost.

Pre-assembly of the receiver 10, retainer 12 and compression insert 14is shown in FIGS. 8-12. With particular reference to FIGS. 8 and 9,first the retainer 12 is inserted into the upper receiver opening 63,leading with the outer surface 107, the top surface 102 facing one arm60 and the retainer bottom surface 104 facing the opposing arm 60. Theretainer 12 is then lowered in such sideways manner into the channel 62and partially into the receiver cavity through the opposed grooves 92,followed by tilting the retainer 12 such that the top surface 102 ismoved into a position within the receiver under the annular surface orledge 87 as best shown in FIG. 10. The retainer 12 is now at leastpartially seated on the receiver spherical surface 80.

Also with reference to FIG. 10 and with further reference to FIGS. 11and 12, the compression insert 14 is then downloaded into the receiver10 through the upper opening 63 with the bottom surface 135 facing thereceiver arm top surfaces 69 and the insert arms 127 located between theopposed receiver arms 60. The insert 14 is then lowered toward thechannel seat 64 until the insert 14 arm upper surfaces 133 are adjacentthe receiver arm inner surfaces 66 located below the guide andadvancement structure 68. Thereafter, the insert 14 is rotated in aclockwise or counter-clockwise manner (see the arrow R) about thereceiver axis B until the upper arm surfaces 133 are directly below theguide and advancement structure 68 of each arm as illustrated in FIGS.11 and 12 with the U-shaped channel 131 of the insert 14 aligned withthe U-shaped channel 62 of the receiver 10. In some embodiments, theinsert arms 127 may need to be compressed slightly during rotation toclear inner surfaces of the receiver arms 60. As shown in FIGS. 12 and13, the insert cylindrical base body 126 is received within thecylindrical surface 88 of the shelf 86 that defines an upper portion ofthe receiver base 58 with lower portions of the arms 127 in contact withthe shelf surface 89. With reference to FIG. 13, the receiver thin walls75 are then crimped inwardly toward the axis B by inserting a tool (notshown) through the receiver apertures 71, the tool pressing the walls 75until the inner wall surfaces engage the insert 14 at the grooves 138formed on the outer surface 137 of each of the insert arms 127 (see,e.g., FIG. 16). The crimping of the walls 75 into the grooves 138 keepsthe insert 14 U-shaped channel 131 aligned with the receiver U-shapedchannel 62. The crimping of the receiver walls 75 prohibits rotation ofthe insert 14 about the receiver axis B but allows for limited axialmovement of the insert 14 with respect to the receiver 10 along the axisB when some force is exerted to slide the insert with respect to thereceiver crimped walls up or down along the grooves 138. The insert 14is fully captured within the receiver 10 by the guide and advancementstructure 68 prohibiting movement of the insert 14 up and out throughthe receiver opening 63 as well as by retainer 12 located below theinsert as shown in FIG. 12. Furthermore, as best shown in FIG. 12,during shipping and handling, the insert 14 prohibits the retainer 12from escaping out of the receiver 10 through the opening 63 and alsoprohibits the retainer from moving out of alignment within the receiverchamber 76, and, in some embodiments from escaping out of the bottomopening 95. The receiver 10, retainer 12 and insert 14 combination isnow pre-assembled and ready for assembly with the shank 4 either at thefactory, by surgery staff prior to implantation, or directly upon animplanted shank 4 as will be described herein.

As illustrated in FIG. 13, the bone screw shank 4 or an entire assembly1 made up of the assembled shank 4, receiver 10, retainer 12 andcompression insert 14, is screwed into a bone, such as the vertebra 13,by rotation of the shank 4 using a suitable driving tool (not shown)that operably drives and rotates the shank body 6 by engagement thereofat the internal drive 50. Specifically, the vertebra 13 may bepre-drilled to minimize stressing the bone and have a guide wire (notshown) inserted therein to provide a guide for the placement and angleof the shank 4 with respect to the vertebra. A further tap hole may bemade using a tap with the guide wire as a guide. Then, the bone screwshank 4 or the entire assembly 1 is threaded onto the guide wireutilizing the cannulation bore 51 by first threading the wire into theopening at the bottom 28 and then out of the top opening at the drivefeature 50. The shank 4 is then driven into the vertebra using the wireas a placement guide. It is foreseen that the shank and other bone screwassembly parts, the rod 21 (also having a central lumen in someembodiments) and the closure top 18 (also with a central bore) can beinserted in a percutaneous or minimally invasive surgical manner,utilizing guide wires. When the shank 4 is driven into the vertebra 13without the remainder of the assembly 1, the shank 4 may either bedriven to a desired final location or may be driven to a locationslightly above or proud to provide for ease in assembly with thepre-assembled receiver, compression insert and retainer.

With further reference to FIG. 13, the pre-assembled receiver, insertand retainer are placed above the shank upper portion 8 until the shankupper portion is received within the opening 95. With particularreference to FIGS. 14 and 15, as the shank upper portion 8 is moved intothe interior 76 of the receiver base, the shank upper portion 8 pressesupwardly against the retainer 12 in the recess partially defined by thecylindrical surface 84. As the portion 8 continues to move upwardlytoward the channel 62, the surface 44 forces outward movement of theretainer 12 towards the cylindrical surface 84 in the receiver expansionchamber or area as the shank 4 presses the retainer 12 against thereceiver lower annular ledge surface 87. The retainer 12 initiallyexpands about the shank upper spherical surface 44 and then slides alongthe cylindrical surface 42, snapping or popping into the recessedcylindrical surface 38, the surface 105 of the retainer 12 fullycontacting and frictionally engaging the cylindrical surface 38 betweenthe shank lower ledge 36 and the upper ledge 40. At this time, theretainer 12 is in a neutral or slightly expanded state, fully snappedonto the shank upper portion 8 with both the retainer 12 and shank upperportion 8 in pivotal relation with the receiver 10.

With reference to FIG. 16, the shank 4 and attached retainer 12 are thenmoved downwardly into a desired position with the retainer seated on thesurface 80. The insert 14 may be pressed downwardly by a tool or by arod and closure top as shown in FIG. 20. In some embodiments, the crimpwalls 75 require that some force is used to press the inert 14downwardly against the shank upper portion 8. In such embodiments, theinsert 14 surface 122 is in frictional engagement with the shank upperportion surface 44 to an extent that the shank is pivotable with respectto the receiver, but in a non-floppy manner. In some embodiments, whenthe receiver 10 is pre-assembled with the shank 4, the entire assembly 1may be implanted at this time by inserting the driving tool (not shown)into the receiver and the shank drive 50 and rotating and driving theshank 4 into a desired location of the vertebra 13.

The rod 21 is eventually positioned in an open or percutaneous manner incooperation with the at least two bone screw assemblies 1. The closurestructure 18 is then inserted into and advanced between the arms 60 ofeach of the receivers 10. The closure structure 18 is rotated, using atool engaged with the inner drive 186 until a selected pressure isreached at which point the rod 21 engages the U-shaped seating surface131 of the compression insert 14, further pressing the insert sphericalsurface 122 against the shank spherical surface 44, pressing the shankupper portion 8 and attached retainer 12 into locked frictionalengagement with the receiver 10. With specific reference to FIGS. 19 and20, as the closure structure 18 rotates and moves downwardly into therespective receiver 10, the point 189 and rim 190 engage and penetratethe rod surface 22, the closure structure 18 pressing downwardly againstand biasing the rod 21 into compressive engagement with the insert 14that urges the shank upper portion 8 and attached retainer 12 intolocking engagement with the receiver, the retainer 12 spherical surface107 frictionally abutting the spherical seating surface 80 of thereceiver 10. For example, about 80 to about 120 inch pounds of torque onthe closure top may be applied for fixing the bone screw shank 6 withrespect to the receiver 10. Also, for example, with reference to FIGS.17 and 18, when the shank 4 is disposed at an angle with respect to thereceiver 10, the lower spherical surface 34 of the shank upper portion 8may also be in frictional engagement with a portion of the receiverspherical seating surface 80. The retainer 12 may also expand slightlyupon locking, providing a full and secure frictional locking engagementwith the receiver at the surface 80.

If removal of the rod 21 from any of the bone screw assemblies 1 isnecessary, or if it is desired to release the rod 21 at a particularlocation, disassembly is accomplished by using the driving tool (notshown) that mates with the internal drive 186 on the closure structure18 to rotate and remove such closure structure from the cooperatingreceiver 10. Disassembly is then accomplished in reverse order to theprocedure described previously herein for assembly.

With reference to FIGS. 21-29 the reference number 201 generallyrepresents a polyaxial bone screw apparatus or assembly according to thepresent invention. The assembly 201 includes a shank 204, that furtherincludes a body 206 integral with an upwardly extending upper portion orcapture structure 208; a receiver 210; a retainer structure 212 and acompression or pressure insert 214. The receiver 210, retainer 212 andcompression insert 214 are initially assembled and may be furtherassembled with the shank 204 either prior or subsequent to implantationof the shank body 206 into a vertebra (not shown), such as the vertebra13 shown in FIG. 13 and described with respect to the assembly 1. FIGS.21 and 28-29 further show a closure structure 218 of the invention forcapturing a longitudinal connecting member, for example, a rod 221 whichin turn engages the compression insert 214 that presses against theshank upper portion 208 and popped-on retainer 212, so as to capture,and fix the longitudinal connecting member 221 within the receiver 210and thus fix the member 221 relative to the vertebra (not shown). Theillustrated rod 221 is hard, stiff, non-elastic and cylindrical, havingan outer cylindrical surface 222. It is foreseen that in otherembodiments, the rod 221 may be elastic, deformable and/or of adifferent cross-sectional geometry as previously described herein withrespect to the rod 21 of the assembly 1. The receiver 210 and the shank204 cooperate in such a manner that the receiver 210 and the shank 204can be secured at any of a plurality of angles, articulations orrotational alignments relative to one another and within a selectedrange of angles both from side to side and from front to rear, to enableflexible or articulated engagement of the receiver 210 with the shank204 until both are locked or fixed relative to each other near the endof an implantation procedure.

The shank 204, best illustrated in FIGS. 21 and 26-29 is substantiallysimilar to the shank 4 previously described herein with respect to theassembly 1. Thus, the shank 204 includes the shank body 206, upperportion or head 208, a shank thread 224, a neck 226, a tip 228, a top ofthread 232, an upper portion lower spherical surface 234 a shelf orledge 236, a cylindrical surface 238, and upper ledge 240 and upperspherical surface 244, a top surface 246, an internal drive 250 and acannulation bore 251 the same or substantially similar to the respectivebody 6, upper portion or head 8, shank thread 24, neck 26, tip 28, topof thread 32, lower spherical surface 34, shelf 36, cylindrical surface38, upper ledge 40, upper spherical surface 44, top surface 46, internaldrive 50 and cannulation bore 51, as well as other features previouslydescribed herein with respect to the shank 4 of the assembly 1.

With particular reference to FIGS. 21, 22 and 24-29, the receiver 210 issubstantially similar to the receiver 10 with the exception of opposedresilient spring tabs 275 that are provided in lieu of the thin walls 75of the receiver 10. As shown in FIG. 25, for example, and discussed ingreater detail below, the spring tabs 275 advantageously resilientlyhold the insert 214 in an upper portion of the receiver until the insert214 is pressed down by the user into a friction fit working positionwherein the insert 214 is in frictional contact with the shank upperportion 208, the shank still movable with respect to the insert, 214,but not in a loose or floppy manner.

The receiver 210 includes a base 258 with integral upstanding arms 260,a U-shaped channel 262 having an upper opening 263 and a lower seat 264,an arm interior substantially cylindrical surface 266, a guide andadvancement structure 268, arm top surfaces 269, an inner base cavity orchamber generally 276, a lower cylindrical surface 278, a sphericalseating surface 280, a lower ledge 282, a central cylindrical portion284, an upper shelf, generally 286 further defined by a lower annularsurface 287, a cylindrical surface 288, and an upper frusto-conicalsurface 289, a pair of opposed grooves 292, a neck 293, a bottom surface294 and a lower opening, generally 295, the same or substantiallysimilar to the respective base 58 with integral upstanding arms 60,U-shaped channel 62, channel upper opening 63 and lower seat 64, arminterior substantially cylindrical surface 66, guide and advancementstructure 68, arm top surfaces 69, inner base cavity or chambergenerally 76, lower cylindrical surface 78, spherical seating surface80, lower ledge 82, central cylindrical portion 84, upper shelf,generally 86 further defined by the lower annular surface 87, thecylindrical surface 88, and the upper frusto-conical surface 89, opposedgrooves 92, neck 93, bottom surface 94 and lower opening 95 of thereceiver 10, and other features previously described herein with respectto the assembly 1.

Extending through each receiver arm 260 is an aperture 271 formed in anarm outer surface 272 and extending through each arm to the innercylindrical surface 266. Each aperture 271 is in the form of asquared-off U-shape, thus forming each of the spring tabs 275 that aresubstantially rectangular in profile. Each tab 275 is integral with therespective receiver arm 260 at a location below and near the guide andadvancement structure 268. Each tab 275 has an inner surface 273 that isan extension of the inner cylindrical surface 266 and is initiallyaligned with the surface 266 as shown, for example, in FIG. 24. A bottomsurface 274 of each tab 275 is spaced from a remainder of the innercylindrical surface 266 that extends downwardly to the shelf 286. Asshown, for example, in FIG. 25, each spring tab 275 is bent inwardlytoward a center axis of the receiver 210 either before or after theinsert 214 is mounted within the receiver 210. In the illustratedembodiment, the tabs 275 are pressed inwardly toward grooves in theinsert 214 after the insert 214 is located within the receiver as shownin FIG. 25 and as will be described in greater detail below.

With reference to FIGS. 21 and 24-29, the retainer 212 is the same orsubstantially similar in form and function to the retainer 12 previouslydescribed herein with respect to the assembly 1. Therefore, the retainer212 includes a central through bore 301, a top surface 302, a bottomsurface 304, an inner cylindrical surface 305, a spherical surface 307and end surfaces 309 and 310 that are the same or similar to therespective central through bore 101, top surface 102, bottom surface104, inner cylindrical surface 105, spherical surface 107 and endsurfaces 109 and 110 previously described herein with respect to theretainer 12.

With reference to FIGS. 21 and 23-29, the compression insert 214 issubstantially similar in form and function to the insert 14 previouslydescribed herein with respect to the assembly 1. The insert 214 differsfrom the insert 14 only in a groove or flat 338 that has a differentgeometry than the groove 138 of the insert 14. Therefore, the insert 214includes an inner cylindrical surface 321, an inner spherical surface322, a cylindrical body 326, a pair of upstanding arms 327, a U-shapedchannel 331 having a lower seat 332, arm top surfaces 333, a bottomsurface 335 and arm outer surfaces 337 that are the same orsubstantially similar to the respective inner cylindrical surface 121,inner spherical surface 122, cylindrical body 126, upstanding arms 127,U-shaped channel 131 with lower seat 132, arm top surfaces 133, thebottom surface 135 and arm outer surfaces 137 of the insert 14previously described herein.

The flat 338 formed in each arm outer surface 337 runs from the topsurface 333 to a lower ledge 340. As shown, for example, in FIG. 26, theflat 338 and the flat lower ledge 340 are sized and shaped to allow theinsert 214 to be moved upwardly adjacent to the guide and advancementstructure 268 during the “popping-on” of the shank 204 into the retainer212 located within the receiver expansion chamber formed within theinner cylindrical surface 284. The receiver spring tabs 275 are insliding frictional engagement with the flats 338 during all of theassembly steps with the shank 204 as well as when the shank 204 ismanipulated with respect to the receiver 210, the insert surface 322 infrictional but movable engagement with the shank surface 244, providingnon-floppy pivoting of the shank 204 with respect to the receiver 210until the shank and receiver are locked together by action of theclosure top 218 pressing against the rod 221 that in turn pressesagainst the insert 214.

With reference to FIGS. 21 and 28-29, the closure top 218 is identicalor substantially similar to the closure top 18 previously describedherein with respect to the assembly 1, having a flange form guide andadvancement structure 382, a top surface 384, an internal drive 386, abase or bottom surface 388, a point 389 and a rim 390 the same orsubstantially similar to the respective guide and advancement structure182, top surface 184, internal drive 186, base or bottom surface 188,point 189 and rim 190 of the closure top 18.

Preferably, the receiver 210, the retainer 212 and the compressioninsert 214 are assembled at a factory setting that includes tooling forholding, alignment and manipulation of the component pieces, as well aspressing the receiver 210 spring tabs 275 toward the insert 214. In somecircumstances, the shank 204 is also assembled with the receiver 210,the retainer 212 and the compression insert 214 at the factory. In otherinstances, it is desirable to first implant the shank 204, followed byaddition of the pre-assembled receiver, retainer and compression insertat the insertion point, similar to what is shown with respect toassembly 1 at FIG. 13. In this way, the surgeon may advantageously andmore easily implant and manipulate the shanks 204, distract or compressthe vertebrae with the shanks and work around the shank upper portionsor heads without the cooperating receivers being in the way. In otherinstances, it is desirable for the surgical staff to pre-assemble ashank of a desired size and/or variety (e.g., surface treatment ofroughening the upper portion 208 and/or hydroxyapatite on the shank206), with the receiver, retainer and compression insert. Allowing thesurgeon to choose the appropriately sized or treated shank 204advantageously reduces inventory requirements, thus reducing overallcost.

Pre-assembly of the compression insert 214 with the receiver 210 andretainer 212 is shown FIGS. 24-25. First, however, the retainer 212 isinserted into the upper receiver opening 263, leading with the outersurface 307, the top surface 302 facing one arm 260 and the retainerbottom surface 304 facing the opposing arm 260. The retainer 212 is thenlowered in such sideways manner into the channel 262 and partially intothe receiver cavity through the opposed grooves 292, followed by tiltingthe retainer 212 such that the top surface 302 is moved into a positionwithin the receiver under the annular surface or ledge 287 and theretainer is at least partially seated on the receiver spherical surface280. Reference is made herein to FIGS. 8-10 showing the insertion of theretainer 12 into the receiver 10 which is accomplished in an identicalmanner to the insertion of the retainer 212 into the receiver 210.

With reference to FIGS. 24 and 25, the compression insert 214 is thendownloaded into the receiver 210 through the upper opening 263 with thebottom surface 335 facing the receiver arm top surfaces 269 and theinsert arms 327 located between the opposed receiver arms 260. Theinsert 214 is then lowered toward the channel seat 264 until the insert214 arm upper surfaces 333 are adjacent the receiver arm inner surfaces266 located below the guide and advancement structure 268. Thereafter,the insert 214 is rotated in a clockwise or counter-clockwise mannerabout the receiver axis until the upper arm surfaces 333 are directlybelow the guide and advancement structure 268 of each arm as illustratedin FIG. 25 with the U-shaped channel 331 of the insert 214 aligned withthe U-shaped channel 262 of the receiver 210. At this time, the receiverspring tabs 275 are pressed and bent inwardly until the spring tabsurfaces 273 frictionally engage the insert flat surfaces 338. At thistime, in some embodiments of the invention, frictional engagementbetween the tabs 275 and the insert surfaces 338 may be used to hold theinsert 214 in an upper portion of the receiver 210, for example as shownin FIG. 26. In other embodiments, the spring tabs 275 function only tohold the insert 214 U-shaped channel 331 in alignment with the receiverU-shaped channel 262. Also, in other embodiments, the spring tabs 275are bent inwardly before the insert 214 is loaded into the receiver, thetabs 275 being resilient enough to be pushed outwardly during rotationof the insert 214 and then snapping onto the flat surfaces 338 once theinsert 214 is rotated into a desired aligned position. In otherembodiments of the invention, the spring tabs 275 may be originallyformed or machined to be directed inwardly and then are sprung outwardlyduring rotation of the insert 214, springing back to a neutral inwardlydirected position once the flats 338 engage the inner surfaces 273 ofthe spring tabs 275. As shown in FIG. 24-27, the receiver spring tabs275 prohibit rotation of the insert 214 about the receiver central axisbut allow for limited up and down movement of the insert 214 withrespect to the receiver 210 along the central axis thereof when someforce is exerted to slide the insert with respect to the receiver springtab surfaces 273 up or down along the flats 338. The insert 214 is fullycaptured within the receiver 210 by the guide and advancement structure268 prohibiting movement of the insert 214 up and out through thereceiver opening 263 as well as by the spring tabs 275 abutting againstthe ledge 340 of the flats 338. Furthermore, similar to what is shownwith respect to the assembly 1 in FIG. 12, during shipping and handling,the insert 214 prohibits the retainer 212 from escaping out of thereceiver 210 through the opening 263 and also prohibits the retainerfrom moving out of alignment within the receiver chamber 276, and, insome embodiments from escaping out of the bottom opening 295. Thereceiver 210, retainer 212 and insert 214 combination is nowpre-assembled and ready for assembly with the shank 204 either at thefactory, by surgery staff prior to implantation, or directly upon animplanted shank 204 as will be described herein.

Similar to the description herein with respect to the assembly 1, thebone screw shank 204 or an entire assembly 201 made up of the assembledshank 204, receiver 210, retainer 212 and compression insert 214, isscrewed into a bone, such as the vertebra 13, by rotation of the shank204 using a suitable driving tool (not shown) that operably drives androtates the shank body 206 by engagement thereof at the internal drive250 and in a percutaneous or minimally invasive surgical manner. Whenthe shank 204 is driven into the vertebra without the remainder of theassembly 201, the shank 204 may either be driven to a desired finallocation or may be driven to a location slightly above or proud toprovide for ease in assembly with the pre-assembled receiver,compression insert and retainer.

With reference to FIGS. 13-15 (directed to identical or substantiallysimilar assembly steps for the assembly 1) and with reference to FIG.26, the pre-assembled receiver, insert and retainer are placed above theshank upper portion 208 until the shank upper portion is received withinthe opening 295. As the shank upper portion 208 is moved into theinterior 276 of the receiver base, the shank upper portion 208 pressesupwardly against the retainer 212 in the recess partially defined by thecylindrical surface 284. As the portion 208 continues to move upwardlytoward the channel 262, the surface 244 forces outward movement of theretainer 212 towards the cylindrical surface 284 in the receiverexpansion chamber or area as the shank 204 presses the retainer 212against the receiver lower annular ledge surface 287. The retainer 212initially expands about the shank upper spherical surface 244 and thenslides along the cylindrical surface 242, snapping or popping into therecessed cylindrical surface 238, the surface 305 of the retainer 212fully contacting and frictionally engaging the cylindrical surface 238between the shank lower ledge 236 and the upper ledge 240. At this time,the retainer 212 is in a neutral or slightly expanded state, fullysnapped onto the shank upper portion 208 with both the retainer 212 andshank upper portion 208 in pivotal relation with the receiver 210.

With reference to FIG. 27, the shank 204 and attached retainer 212 arethen moved downwardly into a desired position with the retainer seatedon the surface 280. The insert 214 may slide downwardly with theretainer 212, or in some embodiments, remain in an upper part of thereceiver 210 retained by the spring tabs 275 until the insert 214 ispressed downwardly by a tool or by a rod and closure top as shown inFIG. 29. In such embodiments, the insert 214 surface 322 is infrictional engagement with the shank upper portion surface 244 to anextent that the shank is pivotable with respect to the receiver, but ina non-floppy manner. In some embodiments, when the receiver 210 ispre-assembled with the shank 204, the entire assembly 201 may beimplanted at this time by inserting the driving tool (not shown) intothe receiver and the shank drive 250 and rotating and driving the shank204 into a desired location of the vertebra, such as the previouslyillustrated vertebra 13.

The rod 221 is eventually positioned in an open or percutaneous mannerin cooperation with the at least two bone screw assemblies 201. Theclosure structure 218 is then inserted into and advanced between thearms 260 of each of the receivers 210. The closure structure 218 isrotated, using a tool engaged with the inner drive 386 until a selectedpressure is reached at which point the rod 221 engages the U-shapedseating surface 331 of the compression insert 214, further pressing theinsert spherical surface 322 against the shank spherical surface 244,pressing the retainer 212 that is attached to the shank upper portion208 into locked frictional engagement with the receiver 210. As theclosure structure 218 rotates and moves downwardly into the respectivereceiver 210, the point 389 and rim 390 engage and penetrate the rodsurface 222, the closure structure 218 pressing downwardly against andbiasing the rod 221 into compressive engagement with the insert 214 thaturges the shank upper portion 208 and attached retainer 212 into lockingengagement with the receiver, the retainer 212 spherical surface 307frictionally abutting the spherical seating surface 280 of the receiver210. For example, about 80 to about 120 inch pounds of torque on theclosure top may be applied for fixing the bone screw shank 206 withrespect to the receiver 210. Also, for example, with reference to FIGS.28 and 29, when the shank 204 is disposed at an angle with respect tothe receiver 210, the lower spherical surface 234 of the shank upperportion 208 may also be in frictional engagement with a portion of thereceiver spherical seating surface 280. The retainer 212 may also expandslightly upon locking, providing a full and secure frictional lockingengagement with the receiver at the surface 280.

If removal of the rod 221 from any of the bone screw assemblies 201 isnecessary, or if it is desired to release the rod 221 at a particularlocation, disassembly is accomplished by using the driving tool (notshown) that mates with the internal drive 386 on the closure structure218 to rotate and remove such closure structure from the cooperatingreceiver 210. Disassembly is then accomplished in reverse order to theprocedure described previously herein for assembly.

With reference to FIGS. 30-39 the reference number 401 generallyrepresents a polyaxial bone screw apparatus or assembly according to thepresent invention. The assembly 401 includes a shank 404, that furtherincludes a body 406 integral with an upwardly extending upper portion orcapture structure 408; a receiver 410; an open retainer structure 412and a compression or pressure insert 414. FIGS. 30 and 37-39 furthershow a closure structure 418 of the invention for capturing alongitudinal connecting member, for example, a deformable rod 421 withinthe receiver 410. The rod 421 may be elastic or inelastic, and isillustrated as a deformable PEEK rod. The assembly 401 is substantiallyidentical to the assembly 1 with a few exceptions. The exceptions are astop block or blocks 540 located on the insert 414, each cooperatingwith a receiver recess having a curved or planar stop wall 470 thatprohibits rotation of the insert 414 with respect to the receiver 410 ina clock-wise manner, providing for secure and sturdy alignment betweenthe insert 414 and the receiver 410 when the closure top 418 is rotatedin a clock-wise manner to press down, not only upon the deformable rod421, but also on the insert 414 as shown in FIG. 38, for example. Thus,even if the PEEK or other deformable rod 421 shifts or deforms withrespect to the closure top 418, the polyaxial mechanism of the assembly401 will remain locked in place because of the locking force of theclosure top 418 on the insert 414 that in turns presses directly againstthe shank as will be described in greater detail below.

With particular reference to FIGS. 30 and 36-39, the shank 404 issubstantially similar in form and function to the shank 4 previouslydescribed herein with respect to the assembly 1. Thus, the shank 404includes the shank body 406, upper portion or head 408, a lowerspherical surface 434, a cylindrical surface 438, an upper cylindricalsurface 442, an upper spherical surface 444 and an internal drive 250that are the same or substantially similar in form and function to therespective body 6, upper portion or head 8, lower spherical surface 34,cylindrical surface 38, upper cylindrical surface 42, upper sphericalsurface 44, internal drive 50, and all the other features previouslydescribed herein with respect to the shank 4 of the assembly 1.

With particular reference to FIGS. 30, 31 and 33-39, the receiver 410 issubstantially similar to the receiver 10 previously described hereinwith the exception of the addition of the recessed stop wall 470mentioned above. Thus, the receiver 410 includes a base 458 withintegral upstanding arms 460, a U-shaped channel 462, arm interiorsubstantially cylindrical surfaces 466, a guide and advancementstructure 468, a pair of opposed tool apertures 471 each partiallydefined by a thin crimp wall 475, an inner base cavity or chambergenerally 476, a lower cylindrical surface 478, a spherical seatingsurface 480, a central cylindrical expansion portion 484 and an uppershelf, generally 486, the same or substantially similar in form andfunction to the respective base 58 with integral upstanding arms 60,U-shaped channel 62, arm interior substantially cylindrical surfaces 66,guide and advancement structure 68, tool apertures 71, crimp walls 75,inner base cavity or chamber generally 76, lower cylindrical surface 78,spherical seating surface 80, central cylindrical expansion portion 84and upper shelf, generally 86, and other features previously describedherein with respect to the receiver 10 of the assembly 1.

With particular reference to FIG. 31, the recess in the receiver that ispartially defined by the blocking wall 470 is formed in each cylindricalinner surface 466 located below the guide and advancement structure 468.The recesses with blocking walls 470 are located opposite one anothersuch that the insert 414 may only be rotated into place in a clock-wisemanner as will be described in more detail below.

With reference to FIGS. 30 and 36-39, the open, expandable retainer 412is the same or substantially similar in form and function to theretainer 12 previously described herein with respect to the assembly 1.Therefore, the retainer 212 includes a top surface 502, a bottom surface504, an inner cylindrical surface 505, an outer spherical surface 507and a through slit 508 that are the same or similar in form and functionto the respective top surface 102, bottom surface 104, inner cylindricalsurface 105, outer spherical surface 107 and slit formed by end surfaces109 and 110 previously described herein with respect to the retainer 12.

With reference to FIGS. 30 and 32-39, the compression insert 414 issubstantially similar in form and function to the insert 14 previouslydescribed herein with respect to the assembly 1 with the exception ofthe addition of the block or stop 540. Therefore, the insert 414includes an inner cylindrical surface 521, an inner spherical surface522, a cylindrical body 526, a pair of upstanding arms 527, a U-shapedchannel 531 having a lower seat 532, arm top surfaces 533, a bottomsurface 535 and arm outer surfaces 537, each with a groove 538 formedtherein that are the same or substantially similar in form and functionto the respective inner cylindrical surface 121, inner spherical surface122, cylindrical body 126, upstanding arms 127, U-shaped channel 131with lower seat 132, arm top surfaces 133, the bottom surface 135 andarm outer surfaces 137 with grooves 138 of the insert 14 previouslydescribed herein. The illustrated embodiment includes two stop blocks540, each formed on the outside surface 537 of each arm 527 and locatednear the arm top surface 533.

With reference to FIGS. 30 and 37-39, the closure top 418 issubstantially similar to the closure top 18 previously described hereinwith respect to the assembly 1 with the exception of the lower rodcontacting surfaces thereof. The closure top 418 has a flange form guideand advancement structure 582, a top surface 584 and an internal drive586 that is the same of substantially similar in form and function tothe respective guide and advancement structure 182, top surface 184 andinternal drive 186 of the closure top 18 previously described herein.The closure top 418 further includes an annular outer base rim 588 and acentral point or nub 589. The nub 589 is located centrally on a domed orspherical surface 590 that is surrounded by and extends from the baserim 588 downwardly away from the closure 418.

The receiver 410 and the retainer 412 are assembled in a manneridentical to what has been described herein with respect to the assemblyof the receiver 10 and the retainer 12. As with the assembly 1,preferably, the receiver 410, the retainer 412 and the compressioninsert 414 are assembled at a factory setting that includes tooling forholding, alignment and manipulation of the component pieces, as well ascrimping the receiver thin walls 475 into the insert grooves 538.

Pre-assembly of the compression insert 414 with the receiver 410 andretainer 412 is shown FIGS. 33-36. The compression insert 414 isdownloaded (see arrow W) into the receiver 410 with the insert arms 527located between the opposed receiver arms 460, the insert 414 beinglowered toward the receiver base 458 until the insert 414 arm uppersurfaces 533 are adjacent the receiver arm inner surfaces 466 locatedbelow the guide and advancement structures 468. Thereafter, the insert414 is rotated in a clockwise direction shown by the arrow X about thereceiver axis until the insert stop blocks 540 abut against each of thereceiver recess stop walls 470. Such occurs when the upper arm surfaces533 are directly below the guide and advancement structure 468 of eacharm as illustrated in FIG. 34 with the U-shaped channel 531 of theinsert 414 aligned with the U-shaped channel 462 of the receiver 410. Atthis time, the receiver thin crimp walls 475 are pressed inwardly intothe insert grooves 538 as shown in FIGS. 35 and 36. At this time, insome embodiments of the invention, frictional engagement between thecrimp walls 475 and the insert surfaces grooves 538 may be used to holdthe insert 414 in an upper portion of the receiver 410, for example asshown in FIG. 36. In addition to holding the insert 414 in a desiredaxial position within the receiver 410, the crimping of the walls 475 inthe grooves 538 prohibits counter-clockwise rotation of the insert 414with respect to the receiver 410.

Similar to the description herein with respect to the assembly 1, thebone screw shank 404 or an entire assembly 401 made up of the assembledshank 404, receiver 410, retainer 412 and compression insert 414, isscrewed into a bone, such as the vertebra 13, by rotation of the shank404 using a suitable driving tool (not shown) that operably drives androtates the shank body 406 by engagement thereof at the internal drive450 and in a percutaneous or minimally invasive surgical manner, orotherwise as desired. When the shank 404 is driven into the vertebrawithout the remainder of the assembly 401, the shank 404 may either bedriven to a desired final location or may be driven to a locationslightly above or proud to provide for ease in assembly with thepre-assembled receiver, compression insert and retainer.

With reference to FIGS. 36-37 (and the discussion previously providedherein with respect to the assembly 1), the pre-assembled receiver,insert and retainer are placed above the shank upper portion 408 and asthe shank upper portion 408 is moved into the interior 476 of thereceiver base, the shank upper portion 408 presses upwardly against theretainer 412 in the expansion recess partially defined by thecylindrical surface 484. As the portion 408 continues to move upwardlytoward the channel 462, the surface 444 forces outward movement of theretainer 412 towards the cylindrical surface 484 in the receiverexpansion chamber or area as the shank 404 presses the retainer 412against the receiver lower annular ledge surface 487. The retainer 412initially expands about the shank upper spherical surface 444 and thenslides along the cylindrical surface 442, snapping or popping into therecessed cylindrical surface 438, the surface 505 of the retainer 412fully contacting and frictionally engaging the cylindrical surface 438between the surfaces 434 and 442. At this time, the retainer 412 is in aneutral or slightly expanded state, fully snapped onto the shank upperportion 408 with both the retainer 412 and shank upper portion 408 inpivotal relation with the receiver 410.

With reference to FIG. 37, the shank 404 and attached retainer 412 arethen moved downwardly into a desired position with the retainer seatedon the surface 480. The insert 414 may slide downwardly with theretainer 412, or in some embodiments, remain in an upper part of thereceiver 410 retained by the crimp walls 475 until the insert 414 ispressed downwardly by a tool or by a rod and closure top. In suchembodiments, the insert 414 surface 522 is in frictional engagement withthe shank upper portion surface 444 to an extent that the shank ispivotable with respect to the receiver, but in a non-floppy manner. Insome embodiments, when the receiver 410 is pre-assembled with the shank404, the entire assembly 401 may be implanted at this time by insertingthe driving tool (not shown) into the receiver and the shank drive 450and rotating and driving the shank 404 into a desired location of thevertebra, such as the previously illustrated vertebra 13.

The rod 421 is eventually positioned in an open or percutaneous mannerin cooperation with the at least two bone screw assemblies 401. Theclosure structure 418 is then inserted into and advanced between thearms 460 of each of the receivers 410. The closure structure 418 isrotated, using a tool engaged with the inner drive 586 until a selectedpressure is reached at which point the rod 421 engages the U-shapedseating surface 531 of the compression insert 414. Also, as shown inFIG. 38, the closure top annular base rim 588 engages and presses downupon top surfaces 533 of the insert 414 arms 527, pressing the insertspherical surface 522 against the shank spherical surface 444, that inturn presses the shank upper portion 408 with attached retainer 412 intolocked frictional engagement with the receiver 410 independently of anylocking pressure placed by the rod 421 onto the insert 414. As theclosure structure 418 rotates and moves downwardly into the respectivereceiver 410, the point or nub 589 and dome 590 engage and penetrate ordeform the rod surface 422, the closure structure 418 pressingdownwardly against and biasing the rod 421 into compressive engagementwith the insert 414 that also urges the shank upper portion 408 andattached retainer 412 into locking engagement with the receiver, theretainer 412 spherical surface 507 frictionally abutting the sphericalseating surface 480 of the receiver 410. For example, about 80 to about120 inch pounds of torque on the closure top may be applied for fixingthe bone screw shank 406 with respect to the receiver 410 by directlocking engagement between the closure top 418, the insert 414, theshank upper portion 408 and attached retainer 412 with the receiverseating surface 480. Over- or undue deformation of the deformable rod421 therefore does not occur because of the direct cooperation betweenthe closure top 418 and the compression insert 414. Also, for example,with reference to FIG. 39, when the shank 404 is disposed at an anglewith respect to the receiver 410, the lower spherical surface 434 of theshank upper portion 408 may also be in frictional engagement with aportion of the receiver spherical seating surface 480. The retainer 412may also expand slightly upon locking, providing a full and securefrictional locking engagement with the receiver at the surface 480.

If removal of the rod 421 from any of the bone screw assemblies 401 isnecessary, or if it is desired to release the rod 421 at a particularlocation, disassembly is accomplished by using the driving tool (notshown) that mates with the internal drive 586 on the closure structure418 to rotate and remove such closure structure from the cooperatingreceiver 410. Disassembly is then accomplished in reverse order to theprocedure described previously herein for assembly.

With reference to FIGS. 40-47 the reference number 601 generallyrepresents a polyaxial bone screw apparatus or assembly according to thepresent invention. The assembly 601 includes a shank 604, that furtherincludes a body 606 integral with an upwardly extending upper portion orcapture structure 608; a receiver 610; an open retainer structure 612and a compression or pressure insert 614. FIGS. 40 and 44-47 furthershow a closure structure 618 of the invention for capturing alongitudinal connecting member, for example, a rod 621 within thereceiver 610. The rod 621 having an outer cylindrical surface 622 may bethe same or substantially similar to the rod 21 or other longitudinalconnecting members previously described herein with respect to theassembly 1. The assembly 601 is substantially identical to the assembly1 with the exception of a feature of the shank 604 and a feature of theretainer 612. Specifically, the shank 604 does not include a lowerspherical surface such as the surface 34 of the shank 4 and the retainer612 inner cylindrical surface further includes inner vertical grooves.

With particular reference to FIGS. 40-42, the shank 604 is substantiallysimilar in form and function to the shank 4 previously described hereinwith respect to the assembly 1, and thus includes the shank body 606,upper portion or head 608, a lower cylindrical surface 638, a ledge 640,an upper cylindrical surface 642, an upper spherical surface 644 and aninternal drive 650 that are the same or substantially similar in formand function to the respective body 6, upper portion or head 8,cylindrical surface 38, ledge 40, upper cylindrical surface 42, upperspherical surface 44, internal drive 50, and all the other featurespreviously described herein with respect to the shank 4 of the assembly1 with the exception of the lower spherical surface 34. The shankcylindrical surface 638 extends from the lower ledge 640 to adjacent aneck 626 that joins the shank upper portion 608 with the shank body 606.

With particular reference to FIGS. 40 and 44-47, the receiver 610 issubstantially similar to the receiver 10 previously described herein andthus includes a base 658 with integral upstanding arms 660, a U-shapedchannel 662, an arm interior substantially cylindrical surface 666, aguide and advancement structure 668, a tool aperture 671 partiallydefined by a thin crimp wall 675, an inner base cavity or chambergenerally 676, a lower cylindrical surface 678, a spherical seatingsurface 680, a central cylindrical expansion portion 684 and an uppershelf, generally 686, the same or substantially similar in form andfunction to the respective base 58 with integral upstanding arms 60,U-shaped channel 62, arm interior substantially cylindrical surface 66,guide and advancement structure 68, tool aperture 71, crimp wall 75,inner base cavity or chamber generally 76, lower cylindrical surface 78,spherical seating surface 80, central cylindrical expansion portion 84and upper shelf, generally 86, and other features previously describedherein with respect to the receiver 10 of the assembly 1.

With particular reference to FIGS. 40, 43 and 44, the open, expandableretainer 612 is the same or substantially similar in form and functionto the retainer 12 previously described herein with respect to theassembly 1, with the addition of inner grooves. Therefore, the retainer612 includes a top surface 702, a bottom surface 704, an innercylindrical surface 705, an outer spherical surface 707 and a throughslit 708 that are the same or similar in form and function to therespective top surface 102, bottom surface 104, inner cylindricalsurface 105, outer spherical surface 107 and slit formed by end surfaces109 and 110 previously described herein with respect to the retainer 12.Formed in the inner surface 705 are four equally spaced grooves 715. Thegrooves 715 aid during the expansion of the retainer 612 and furthermorein resiliency and gripping of the retainer 612 on the shank surface 638.As compared to the retainer 12, the spaced grooves 715 of the retainer612 provide for a more even expansion during assembly with the shankupper portion 608, resulting in less stress in the area directlyopposite the slit 708. The retainer 612 also requires less space forexpansion about the upper portion 608 since not all of the expansion isoccurring opposite the slit 708, but rather at each of the grooves 715.Less stress during expansion results in a stronger retainer 12post-expansion.

With reference to FIGS. 40, 44, 45 and 47, the compression insert 614 issubstantially similar in form and function to the insert 14 previouslydescribed herein with respect to the assembly 1. Therefore, the insert614 includes an inner cylindrical surface 721, an inner sphericalsurface 722, a cylindrical body 726, a pair of upstanding arms 727, aU-shaped channel 731 having a lower seat 732, arm top surfaces 733, abottom surface 735 and arm outer surfaces 737, each with a groove 738formed therein that are the same or substantially similar in form andfunction to the respective inner cylindrical surface 121, innerspherical surface 122, cylindrical body 126, upstanding arms 127,U-shaped channel 131 with lower seat 132, arm top surfaces 133, thebottom surface 135 and arm outer surfaces 137 with grooves 138 of theinsert 14 previously described herein.

With reference to FIGS. 40 and 44-47, the closure top 618 is identicalto the closure top 18 previously described herein with respect to theassembly 1 with the exception of the lower rod contacting surfacesthereof. The closure top 618 has a flange form guide and advancementstructure 782, a top surface 784, an internal drive 786, a bottomsurface 788, a point 789 and a rim 790 that is the same in form andfunction to the respective guide and advancement structure 182, topsurface 184, internal drive 186, base 188, point 189 and rim 190 of theclosure top 18 previously described herein.

The assembly and disassembly, if desired, and implantation and operationof the assembly 601 is performed in a manner identical to what has beendescribed herein with respect to the assembly 1. In operation, theretainer 612 inner surface 705 grips the shank surface 638 with theretainer top surface 702 abutting against the shank ledge 640 as shown,for example, in FIGS. 44-47. The downward force applied on the shankupper spherical surface 644 by the compression insert surface 722maintains the retainer 612 in engagement with the ledge 640 as theretainer spherical surface 707 is pressed against the receiver seatingsurface 680 at all desired angles of articulation between the shank 604and the receiver 610 as shown, for example, in FIG. 47.

With reference to FIGS. 48-51 the reference number 801 generallyrepresents a polyaxial bone screw apparatus or assembly according to thepresent invention. The assembly 801 includes a shank 804, that furtherincludes a body 806 integral with an upwardly extending upper portion orcapture structure 808; a receiver 810; an open retainer structure 812and a compression or pressure insert 814. FIGS. 48, 49 and 51 furthershow a closure structure 818 of the invention for capturing alongitudinal connecting member, for example, a rod 821 within thereceiver 810. The rod 821 is the same or substantially similar to therod 21 or other longitudinal connecting members previously describedherein with respect to the assembly 1. The assembly 801 is a combinationof the assembly 201 and the assembly 601, both previously describedherein. Specifically, the shank 804, the retainer 812 and the closuretop 818 are identical or substantially similar to the respective shank604, retainer 612 and closure top 618 of the assembly 601 while thereceiver 810 and the compression insert 814 are identical orsubstantially similar to the respective receiver 210 and insert 214 ofthe assembly 201. In other words, the assembly 801 is identical to thepreviously described assembly 601 with the exception that receiverspring tabs 275 and insert flat surface portions 338 of the assembly 201have replaced the receiver crimp walls 678 and insert grooves 738 of theassembly 601. The assembly 801 has designated spring tabs 875 andcooperating insert flat surface portions 838. The assembly anddisassembly, if desired, and implantation and operation of the assembly801 is performed in a manner identical to what has been described hereinwith respect to the assembly 201.

With reference to FIGS. 52-54 the reference number 901 generallyrepresents a polyaxial bone screw apparatus or assembly according to thepresent invention. The assembly 901 includes a shank 904, that furtherincludes a body 906 integral with an upwardly extending upper portion orcapture structure 908; a receiver 910; an open retainer structure 912and a compression or pressure insert 914. FIGS. 52-54 further show aclosure structure 918 of the invention for capturing a longitudinalconnecting member, for example, a deformable rod 921 within the receiver910. The rod 921 is the same or substantially similar to the rod 421previously described herein with respect to the assembly 401. Theassembly 901 is a combination of the assembly 401 and the assembly 601.Specifically, the shank 904 and the retainer 912 are identical orsubstantially similar to the respective shank 604 and retainer 612 ofthe assembly 601 while the receiver 910, the compression insert 914 andthe closure top 918 are identical or substantially similar to therespective receiver 410, insert 414 and closure top 418 of the assembly401. The assembly and disassembly, if desired, and implantation andoperation of the assembly 901 is performed in a manner identical to whathas been described herein with respect to the assembly 401.

With reference to FIGS. 55-58, an alternative open retainer 12′ for usewith any of the other assemblies described herein is substantiallysimilar to the open retainer 12 previously described herein with theexception of grooves formed in the retainer 12′. Specifically, theretainer 12′ includes a top surface 102′, a bottom surface 104′, aninner cylindrical surface 105′, an outer spherical surface 107′ and endsurfaces 109′ and 110′ that are the same or similar in form and functionto the respective top surface 102, bottom surface 104, inner cylindricalsurface 105, outer spherical surface 107 and slit formed by end surfaces109 and 110 previously described herein with respect to the retainer 12.Furthermore, four evenly spaced grooves 115′ are formed in the bottomsurface 104′ and extend through the inner surface 105′ and the outerspherical surface 107′ about halfway toward the top surface 102′. It isforeseen that there may be more or fewer groves 115′. The grooves 115′advantageously even out the stress on the retainer 12′ during expansionthereof over a shank upper portion 8, 208, 408, 608, 808 or 908previously described herein. Thus, the grooves 115′ aid in making theretainer 12′ more strong and resilient, deforming outwardly duringexpansion in a more even or uniform fashion at the grooves 115′,resulting in less stress at the portion of the retainer located directlyopposite the slit formed by the end surfaces 109′ and 110′.

With reference to FIGS. 59-60 the reference number 1001 generallyrepresents a polyaxial bone screw apparatus or assembly according to thepresent invention. The assembly 1001 includes a shank 1004, that furtherincludes a body 1006 integral with an upwardly extending upper portionor capture structure 1008; a receiver 1010; an open retainer structure1012 and a compression or pressure insert 1014. FIGS. 59 and 60 furthershow a closure structure 1018 of the invention for capturing alongitudinal connecting member, for example, a rod 1021 within thereceiver 1010. The rod 1021 is the same or substantially similar to therod 21 or other longitudinal connecting members previously describedherein with respect to the assembly 1. The receiver 1010, the insert1014, the closure top 1018 and the rod 1021 are identical orsubstantially similar to the respective receiver 210, insert 214,closure top 218 and rod 221 previously described herein with respect tothe assembly 201 shown in FIGS. 21-29 and previously described herein.The shank 1004 and the retainer 1012 are similar to the respective shank204 and retainer 212 of the assembly 201, but there are somedifferences. Primarily, the shank and retainer have been modified tohave a frusto-conical interface as compared to the cylindrical interfaceshown between the shank 204 and the retainer 212.

Specifically, the shank 1004, having the shank body 1006 includes ahelically wound bone implantable thread 1024 (single or dual lead threadform) extending from near a neck 1026 located adjacent to the upperportion or capture structure 1008, to a tip 1028 of the body 1006 andextending radially outwardly therefrom. The neck 1026 extends axiallyupward from the shank body 1006. The neck 1026 may be of the same or istypically of a slightly reduced radius as compared to an adjacent upperend or top 1032 of the body 1006 where the thread 1024 terminates.Further extending axially and outwardly from the neck 1026 is the shankupper portion 1008 that provides a connective or capture apparatusdisposed at a distance from the upper end 1032 and thus at a distancefrom a vertebra, such as the vertebra 13 when the body 1006 is implantedin such vertebra.

The shank upper portion 1008 is configured for a pivotable connectionbetween the shank 1004 (with attached retainer 1012) and the receiver1010 prior to fixing of the shank 1004 in a desired position withrespect to the receiver 1010. The shank upper portion 1008 has an outer,convex and substantially spherical lower surface 1034 that extendsoutwardly and upwardly from the neck 1026 and terminates at afrusto-conical surface 1038. In some embodiments of the invention, thespherical lower surface 1034 has an outer radius that is the same orsubstantially similar to an outer radius of the retainer 1012 so thatthe surface 1034 as well as the retainer 1012 outer surfaceparticipating in the ball and socket joint formed by the shank 1004 andattached retainer 1012 within the partially spherical surface definingan inner cavity of the receiver 1010. However, in other embodiments, theradius of the shank portion 1034 may be different than a radius of theretainer 1012. Adjacent the spherical surface 1034 is the upwardly andinwardly extending frusto-conical surface 1038. Extending outwardly fromthe frusto-conical surface 1038 is an annular surface or upper ledge1040 that faces downwardly toward the frusto-conical surface 1038 and issubstantially perpendicular to a central axis of the shank 1004. Thefrusto-conical surface 1038 and the upper ledge 1040 cooperate tocapture and fix the resilient open retainer 1012 to the shank upperportion 1008, prohibiting movement of the retainer 1012 along the shankaxis once the retainer 1012 is located beneath ledge 1040. Theillustrated frusto-conical surface 1038 is narrower at a top thereof. Inother words, a diameter of the surface 1038 near the upper ledge 1040 issmaller than a diameter of the surface 1038 near the lower sphericalsurface 1034. Extending upwardly from the upper ledge 1040 is aspherical or domed surface 1044. The spherical surface 1044 has an outerradius configured for sliding cooperation and ultimate frictional matingwith a substantially spherical concave surface of the compression insert1014 that has the same or substantially similar radius as the surface1044. The radius of the surface 1044 is smaller than the radius of thelower spherical surface 1034. Located near or adjacent to the surface1044 is an annular top surface 1046. A counter sunk internal drivefeature 1050 is formed in the top surface 1046 and has a hex shapedesigned to receive a hex tool (not shown) of an Allen wrench type, intothe aperture for rotating and driving the bone screw shank 1004.

The open retainer 1012 that operates to capture the shank upper portion1008 within the receiver 1010 is made from a resilient material, such asa stainless steel or titanium alloy, so that the retainer 1012 may beexpanded during assembly. However, because there is no need to compressthe retainer 1012 during assembly, an opening or slit, generally 1108that allows for expansion of the retainer 1012 is designed to be verynarrow, advantageously providing substantial or almost full surfacecontact between the retainer and the shank upper portion 1008 and alsobetween the retainer and the receiver 1010 seating surface. The retainer1012 has a central channel or hollow through bore that passes entirelythrough the structure 1012 from a top surface 1102 to a bottom surface1104 thereof. The bore is primarily defined by a discontinuous innerfrusto-conical surface 1105 that runs from the top surface 1102 to thebottom surface 1104. The retainer 1012 further includes an outersubstantially spherical surface 1107 running between the top surface1102 and the bottom surface 1104, the surface 1107 having the same orsimilar radius (when the resilient retainer 1012 is in a non-expanded,neutral or near neutral state) as the receiver 1010 seating surface andthe shank lower spherical surface 1034 and thus larger than the radiusof the dome 1044 of the shank 1004 that engages the similarly radiusedlower surface of the insert 1014. The resilient retainer 1012 furtherincludes first and second end surfaces disposed in spaced relation toone another forming the slit 1108 when the retainer is in a neutral ornear neutral state.

The assembly 1001 is assembled in a manner similar to the assembly 1,201 and 601, for example, as previously described herein, with the shankupper portion 1008 being snapped or popped into the receiver 1010 bypushing the shank spherical surface 1044 through the retainer 1012already located within the receiver inner cavity. As shown in FIG. 60,once assembled, the frusto-conical surface 1038 of the shank 1004contacts the frusto-conical surface 1105 of the retainer 1012 with theretainer top surface 1102 abutting against the shank ledge surface 1040,providing a secure fit between the shank 1004 and the retainer 1012, theretainer 1012 thus capturing the shank head 1008 within the receiver1010. Further assembly and disassembly, if desired, and implantation andoperation of the assembly 1001 is performed in a manner identical towhat has been described herein with respect to the assemblies 1, 201,601 and 801, for example.

With reference to FIGS. 61-62 the reference number 2001 generallyrepresents another polyaxial bone screw apparatus or assembly accordingto the present invention. The assembly 2001 includes a shank 2004, thatfurther includes a body 2006 integral with an upwardly extending upperportion or capture structure 2008; a receiver 2010; an open retainerstructure 2012 and a compression or pressure insert 2014. FIGS. 61 and62 further show a closure structure 2018 of the invention for capturinga longitudinal connecting member, for example, a rod 2021 within thereceiver 2010. The rod 2021 is the same or substantially similar to therod 21 or other longitudinal connecting members previously describedherein with respect to the assembly 1. The receiver 2010, the insert2014, the closure top 2018 and the rod 2021 are identical orsubstantially similar to the respective receiver 10, insert 14, closuretop 18 and rod 21 previously described herein with respect to theassembly 1 shown in FIGS. 1-20 and previously described herein. Theshank 2004 and the retainer 2012 are similar to the respective shank 4and retainer 12 of the assembly 1, but there are some differences.Primarily, the shank and retainer have been modified to have afrusto-conical interface as compared to the cylindrical interface shownbetween the shank 4 and the retainer 12.

Specifically, the shank 2004, having the shank body 2006 includes ahelically wound bone implantable thread 2024 (single or dual lead threadform) extending from near a neck 2026 located adjacent to the upperportion or capture structure 2008, to a tip 2028 of the body 2006 andextending radially outwardly therefrom. The neck 2026 extends axiallyupward from the shank body 2006. The neck 2026 may be of the same or istypically of a slightly reduced radius as compared to an adjacent upperend or top 2032 of the body 2006 where the thread 2024 terminates.Further extending axially and outwardly from the neck 2026 is the shankupper portion 2008 that provides a connective or capture apparatusdisposed at a distance from the upper end 2032 and thus at a distancefrom a vertebra, such as the vertebra 13 when the body 2006 is implantedin such vertebra.

The shank upper portion 2008 is configured for a pivotable connectionbetween the shank 2004 (with attached retainer 2012) and the receiver2010 prior to fixing of the shank 2004 in a desired position withrespect to the receiver 2010. The shank upper portion 2008 has an outer,convex and substantially spherical lower surface 2034 that. extendsoutwardly and upwardly from the neck 2026 and terminates at a lowerledge 2036. The spherical lower surface 2034 has an outer radius that isthe same or substantially similar to an outer radius of the retainer2012, the surface 2034 as well as the retainer 2012 outer surfaceparticipating in the ball and socket joint formed by the shank 2004 andattached retainer 2012 within the partially spherical surface definingan inner cavity of the receiver 2010. Adjacent the surface 2034 is theannular, planar lower ledge surface 2036 positioned perpendicular to acentral axis of the shank 2004. Extending outwardly and upwardly fromthe lower ledge 2036 is a frusto-conical surface 2038. Extending fromthe frusto-conical surface 2038 is an annular surface or upper ledge2040 that is opposite the lower ledge 2036, and faces downwardly towardthe frusto-conical surface 2038, the upper ledge 2040 also beingsubstantially perpendicular to the central axis of the shank 2004. Thefrusto-conical surface 2038 and the upper and lower ledges 2036 and 2040cooperate to capture and fix the resilient open retainer 2012 to theshank upper portion 2008, prohibiting movement of the retainer 2012along the shank axis once the retainer 2012 is located between theledges 2036 and 2040. The illustrated frusto-conical surface 2038 isnarrower at a bottom thereof. In other words, a diameter of the surface2038 near the upper ledge 2040 is larger than a diameter of the surface2038 near the bottom ledge 2036. Extending upwardly from the upper ledge2040 is a spherical or domed surface 2044. The spherical surface 2044has an outer radius configured for sliding cooperation and ultimatefrictional mating with a substantially spherical concave surface of thecompression insert 2014 that has the same or substantially similarradius as the surface 2044. The radius of the surface 2044 is smallerthan the radius of the lower spherical surface 2034. Located near oradjacent to the surface 2044 is an annular top surface 2046. A countersunk internal drive feature 2050 is formed in the top surface 2046 andhas a hex shape designed to receive a hex tool (not shown) of an Allenwrench type, into the aperture for rotating and driving the bone screwshank 2004.

The open retainer 2012 that operates to capture the shank upper portion2008 within the receiver 2010 is made from a resilient material, such asa stainless steel or titanium alloy, so that the retainer 2012 may beexpanded during assembly. However, because there is no need to compressthe retainer 2012 during assembly, an opening or slit, generally 2108that allows for expansion of the retainer 2012 is designed to be verynarrow, advantageously providing substantial or almost full surfacecontact between the retainer and the shank upper portion 2008 and alsobetween the retainer and the receiver 2010 seating surface. The retainer2012 has a central channel or hollow through bore that passes entirelythrough the structure 2012 from a top surface 2102 to a bottom surface2104 thereof. The bore is primarily defined by a discontinuous innerfrusto-conical surface 2105 that runs from the top surface 2102 to thebottom surface 2104. The retainer 2012 further includes an outersubstantially spherical surface 2107 running between the top surface2102 and the bottom surface 2104, the surface 2107 having the same orsimilar radius (when in a neutral or near neutral state) as the receiver2010 seating surface and the shank lower spherical surface 2034 and thuslarger than the radius of the dome 2044 of the shank 2004 that engagesthe similarly radiused lower surface of the insert 2014. The resilientretainer 2012 further includes first and second end surfaces disposed inspaced relation to one another forming the slit 2108 when the retaineris in a neutral or near neutral state.

The assembly 2001 is assembled in a manner similar to the assembly 1,for example, as previously described herein, with the shank upperportion 2008 being snapped or popped into the receiver 2010 by pushingthe shank spherical surface 2044 through the retainer 2012 alreadylocated within the receiver inner cavity. As shown in FIG. 62, onceassembled, the frusto-conical surface 2038 of the shank 2004 contactsthe frusto-conical surface 2105 of the retainer 2012 with the retainerbottom surface 2104 seated on the shank lower ledge surface 2036 and aportion of the retainer top surface 2102 abutting against the shankupper ledge surface 2040, providing a secure fit between the shank 2004and the retainer 2012, the retainer 2012 thus capturing the shank head2008 within the receiver 2010. Further assembly and disassembly, ifdesired, and implantation and operation of the assembly 2001 isperformed in a manner identical to what has been described herein withrespect to the assemblies 1, 201, 601 and 801, for example.

With reference to FIGS. 63-64 the reference number 3001 generallyrepresents another polyaxial bone screw apparatus or assembly accordingto the present invention. The assembly 3001 includes a shank 3004, thatfurther includes a body 3006 integral with an upwardly extending upperportion or capture structure 3008; a receiver 3010; an open retainerstructure 3012 and a compression or pressure insert 3014. FIGS. 63 and64 further show a closure structure 3018 of the invention for capturinga longitudinal connecting member, for example, a rod 3021 within thereceiver 3010. The rod 3021 is the same or substantially similar to therod 21 or other longitudinal connecting members previously describedherein with respect to the assembly 1. The receiver 3010, the insert3014, the closure top 3018 and the rod 3021 are identical orsubstantially similar to the respective receiver 210, insert 214,closure top 218 and rod 221 previously described herein with respect tothe assembly 201 shown in FIGS. 21-29 and previously described herein.The shank 3004 and the retainer 3012 are similar to the respective shank204 and retainer 212 of the assembly 201, but there are somedifferences. Primarily, the shank and retainer have been modified tohave a sloping and curved interface as compared to the cylindricalinterface shown between the shank 204 and the retainer 212.

Specifically, the shank 3004, having the shank body 3006 includes ahelically wound bone implantable thread 3024 (single or dual lead threadform) extending from near a neck 3026 located adjacent to the upperportion or capture structure 3008, to a tip 3028 of the body 3006 andextending radially outwardly therefrom. The neck 1026 extends axiallyupward from the shank body 1006. The neck 3026 may be of the same or istypically of a slightly reduced radius as compared to an adjacent upperend or top 3032 of the body 3006 where the thread 3024 terminates.Further extending axially and outwardly from the neck 3026 is the shankupper portion 3008 that provides a connective or capture apparatusdisposed at a distance from the upper end 3032 and thus at a distancefrom a vertebra, such as the vertebra 13 when the body 3006 is implantedin such vertebra.

The shank upper portion 3008 is configured for a pivotable connectionbetween the shank 31004 (with attached retainer 3012) and the receiver3010 prior to fixing of the shank 3004 in a desired position withrespect to the receiver 3010. The shank upper portion 3008 has an outer,convex and substantially spherical lower surface 3034 that extendsoutwardly and upwardly from the neck 3026 and terminates at a curvedsurface 3038. The spherical lower surface 3034 has an outer radius thatis the same or substantially similar to an outer radius of the retainer3012 so that the surface 3034 as well as the retainer 3012 outer surfaceparticipating in the ball and socket joint formed by the shank 3004 andattached retainer 3012 within the partially spherical surface definingan inner cavity of the receiver 3010. Adjacent the spherical surface3034 the an upwardly and inwardly extending curved surface of revolution3038 formed about a central axis of the shank 3004, the illustratedsurface 3038 being somewhat trumpet-like in form, having at least oneand up to a plurality a radii. Extending outwardly from the surface 3038is an annular surface or upper ledge 3040 that faces downwardly towardthe curved surface 3038 and is substantially perpendicular to thecentral axis of the shank 3004. The curved surface 3038 and the upperledge 3040 cooperate to capture and fix the resilient open retainer 3012to the shank upper portion 3008, prohibiting movement of the retainer3012 along the shank axis once the retainer 3012 is located beneathledge 3040. The illustrated curved surface 3038 is narrower at a topthereof. In other words, a diameter of the surface 3038 near the upperledge 3040 is smaller than a diameter of the surface 3038 near the lowerspherical surface 3034. Extending upwardly from the upper ledge 3040 isa spherical or domed surface 3044. The spherical surface 3044 has anouter radius configured for sliding cooperation and ultimate frictionalmating with a substantially spherical concave surface of the compressioninsert 3014 that has the same or substantially similar radius as thesurface 3044. The radius of the surface 3044 is smaller than the radiusof the lower spherical surface 3034. Located near or adjacent to thesurface 3044 is an annular top surface 3046. A counter sunk internaldrive feature 3050 is formed in the top surface 3046 and has a hex shapedesigned to receive a hex tool (not shown) of an Allen wrench type, intothe aperture for rotating and driving the bone screw shank 3004.

The open retainer 3012 that operates to capture the shank upper portion3008 within the receiver 3010 is made from a resilient material, such asa stainless steel or titanium alloy, so that the retainer 3012 may beexpanded during assembly. However, because there is no need to compressthe retainer 3012 during assembly, an opening or slit, generally 3108that allows for expansion of the retainer 3012 is designed to be verynarrow, advantageously providing substantial or almost full surfacecontact between the retainer and the shank upper portion 3008 and alsobetween the retainer and the receiver 3010 seating surface. The retainer3012 has a central channel or hollow through bore that passes entirelythrough the structure 3012 from a top surface 3102 to a bottom surface3104 thereof. The bore is primarily defined by a discontinuous innercurved surface of rotation 3105 that runs from the top surface 3102 tothe bottom surface 3104. The retainer 3012 further includes an outersubstantially spherical surface 3107 running between the top surface3102 and the bottom surface 3104, the surface 3107 having the same orsimilar radius (when the resilient retainer 3012 is in a non-expanded,neutral or near neutral state) as the receiver 3010 seating surface andthe shank lower spherical surface 3034 and thus larger than the radiusof the dome 3044 of the shank 3004 that engages the similarly radiusedlower surface of the insert 3014. The resilient retainer 3012 furtherincludes first and second end surfaces disposed in spaced relation toone another forming the slit 3108 when the retainer is in a neutral ornear neutral state.

The assembly 3001 is assembled in a manner similar to the assembly 1,201 and 601, for example, as previously described herein, with the shankupper portion 3008 being snapped or popped into the receiver 3010 bypushing the shank spherical surface 3044 through the retainer 3012already located within the receiver inner cavity. As shown in FIG. 64,once assembled, the curved surface 3038 of the shank 3004 matches and isin mating contact with the curved surface 3105 of the retainer 3012 witha portion of the retainer top surface 3102 abutting against the shankledge surface 3040, providing a secure fit between the shank 3004 andthe retainer 3012, the retainer 3012 thus capturing the shank head 3008within the receiver 3010. Further assembly and disassembly, if desired,and implantation and operation of the assembly 3001 is performed in amanner identical to what has been described herein with respect to theassemblies 1, 201, 601 and 801, for example.

With reference to FIGS. 65-66 the reference number 4001 generallyrepresents another polyaxial bone screw apparatus or assembly accordingto the present invention. The assembly 4001 includes a shank 4004, thatfurther includes a body 4006 integral with an upwardly extending upperportion or capture structure 4008; a receiver 4010; an open retainerstructure 4012 and a compression or pressure insert 4014. FIGS. 65 and66 further show a closure structure 4018 of the invention for capturinga longitudinal connecting member, for example, a rod 4021 within thereceiver 4010. The rod 4021 is the same or substantially similar to therod 21 or other longitudinal connecting members previously describedherein with respect to the assembly 1. The receiver 4010, the insert4014, the closure top 4018 and the rod 4021 are identical orsubstantially similar to the respective receiver 10, insert 14, closuretop 18 and rod 21 previously described herein with respect to theassembly 1 shown in FIGS. 1-20 and previously described herein. Theshank 4004 and the retainer 4012 are similar to the respective shank 4and retainer 12 of the assembly 1, but there are some differences.Primarily, the shank and retainer have been modified to have a curved,surface of rotation interface as compared to the cylindrical interfaceshown between the shank 4 and the retainer 12.

Specifically, the shank 4004, having the shank body 4006 includes ahelically wound bone implantable thread 4024 (single or dual lead threadform) extending from near a neck 4026 located adjacent to the upperportion or capture structure 4008, to a tip 4028 of the body 4006 andextending radially outwardly therefrom. The neck 4026 extends axiallyupward from the shank body 4006. The neck 4026 may be of the same or ofa slightly reduced radius as compared to an adjacent upper end or top4032 of the body 4006 where the thread 4024 terminates. Furtherextending axially and outwardly from the neck 4026 is the shank upperportion 4008 that provides a connective or capture apparatus disposed ata distance from the upper end 4032 and thus at a distance from avertebra, such as the vertebra 13 when the body 4006 is implanted insuch vertebra.

The shank upper portion 4008 is configured for a pivotable connectionbetween the shank 4004 (with attached retainer 4012) and the receiver4010 prior to fixing of the shank 4004 in a desired position withrespect to the receiver 4010. The shank upper portion 4008 has an outer,convex and substantially spherical lower surface 4034 that extendsoutwardly and upwardly from the neck 4026 and terminates at an annularsurface 4036. The spherical lower surface 4034 has an outer radius thatis the same or substantially similar to an outer radius of the retainer4012, the surface 4034 as well as the retainer 4012 outer surfaceparticipating in the ball and socket joint formed by the shank 4004 andattached retainer 4012 within the partially spherical surface definingan inner cavity of the receiver 4010. Adjacent the surface 4034 is theannular, planar lower ledge surface 4036 positioned perpendicular to acentral axis of the shank 4004. Extending outwardly and upwardly fromthe lower ledge 4036 is a curved surface of rotation 4038 formed aboutthe shank central axis. Unlike the trumpet like surface 3038 previouslydescribed with respect to the assembly 3001, the surface 4038 isuniform, defined by a curve with a single radius. Extending from thecurved surface 4038 is an annular surface or upper ledge 4040 that isopposite the lower ledge 4036, and faces downwardly toward the curvedsurface 4038, the upper ledge 4040 also being substantiallyperpendicular to the central axis of the shank 4004. The curved surface4038 and the upper and lower ledges 4036 and 4040 cooperate to captureand fix the resilient open retainer 4012 to the shank upper portion4008, prohibiting movement of the retainer 4012 along the shank axisonce the retainer 4012 is located between the ledges 4036 and 4040.Extending upwardly from the upper ledge 4040 is a spherical or domedsurface 4044. The spherical surface 4044 has an outer radius configuredfor sliding cooperation and ultimate frictional mating with asubstantially spherical concave surface of the compression insert 4014that has the same or substantially similar radius as the surface 4044.The radius of the surface 4044 is smaller than the radius of the lowerspherical surface 4034 and the outer radius of the retainer 4012.Located near or adjacent to the surface 4044 is an annular top surface4046. A counter sunk internal drive feature 4050 is formed in the topsurface 4046 and has a hex shape designed to receive a hex tool (notshown) of an Allen wrench type, into the aperture for rotating anddriving the bone screw shank 4004.

The open retainer 4012 that operates to capture the shank upper portion4008 within the receiver 4010 is made from a resilient material, such asa stainless steel or titanium alloy, so that the retainer 4012 may beexpanded during assembly. However, because there is no need to compressthe retainer 4012 during assembly, an opening or slit, generally 4108that allows for expansion of the retainer 4012 is designed to be verynarrow, advantageously providing substantial or almost full surfacecontact between the retainer and the shank upper portion 4008 and alsobetween the retainer and the receiver 4010 seating surface. The retainer4012 has a central channel or hollow through bore that passes entirelythrough the structure 4012 from a top surface 4102 to a bottom surface4104 thereof. The bore is primarily defined by a discontinuous innercurved surface 4105 that runs from the top surface 4102 to the bottomsurface 4104. The retainer 4012 further includes an outer substantiallyspherical surface 4107 running between the top surface 4102 and thebottom surface 4104, the surface 4107 having the same or similar radius(when in a neutral or near neutral state) as the receiver 4010 seatingsurface and the shank lower spherical surface 4034 and thus larger thanthe radius of the dome 4044 of the shank 4004 that engages the insert4014. The resilient retainer 4012 further includes first and second endsurfaces disposed in spaced relation to one another forming the slit4108 when the retainer is in a neutral or near neutral state.

The assembly 4001 is assembled in a manner similar to the assembly 1,for example, as previously described herein, with the shank upperportion 4008 being snapped or popped into the receiver 4010 by pushingthe shank spherical surface 4044 through the retainer 4012 alreadylocated within the receiver inner cavity. As shown in FIG. 66, onceassembled, the curved surface 4038 of the shank 4004 aligns and closelycontacts the curved surface 4105 the retainer 4012 with the retainerbottom surface 4104 seated on the shank lower ledge surface 4036 and aportion of the retainer top surface 4102 abutting against the shankupper ledge surface 4040, providing a secure fit between the shank 4004and the retainer 4012, the retainer 4012 thus capturing the shank head4008 within the receiver 4010. Further assembly and disassembly, ifdesired, and implantation and operation of the assembly 4001 isperformed in a manner identical to what has been described herein withrespect to the assemblies 1, 201, 601 and 801, for example.

With reference to FIGS. 67-68 the reference number 5001 generallyrepresents another polyaxial bone screw apparatus or assembly accordingto the present invention. The assembly 5001 includes a shank 5004, thatfurther includes a body 5006 integral with an upwardly extending upperportion or capture structure 5008; a receiver 5010; an open retainerstructure 5012 and a compression or pressure insert 5014. FIGS. 67 and68 further show a closure structure 5018 of the invention for capturinga longitudinal connecting member, for example, a rod 5021 within thereceiver 5010. The rod 5021 is the same or substantially similar to therod 21 or other longitudinal connecting members previously describedherein with respect to the assembly 1. The receiver 5010, the insert5014, the closure top 5018 and the rod 5021 are substantially similar tothe respective receiver 10, insert 14, closure top 18 and rod 21previously described herein with respect to the assembly 1 shown inFIGS. 1-20 and previously described herein. It is noted that toaccommodate the slightly taller retainer 5012, the receiver 5010interior has also been slightly modified to create a slightly tallerinner expansion chamber for the expansion of the retainer 5012 about theshank head 5008 within such chamber. The shank 5004 and the retainer5012 are similar to the respective shank 4 and retainer 12 of theassembly 1, but there are some differences. Primarily, the shank andretainer have been modified to provide an assembly wherein the retainer5012 has an outer radius that is the same as an upper outer radius ofthe shank 5010 that in turn engages the insert 5014 at a lower concavesurface thereof, also having the same radius.

Specifically, the shank 5004, having the shank body 5006 includes ahelically wound bone implantable thread 5024 (single or dual lead threadform) extending from near a neck 5026 located adjacent to the upperportion or capture structure 5008, to a tip 5028 of the body 5006 andextending radially outwardly therefrom. The neck 5026 extends axiallyupward from the shank body 5006. The neck 5026 may be of the same or ofa slightly reduced radius as compared to an adjacent upper end or top5032 of the body 5006 where the thread 5024 terminates. Furtherextending axially and outwardly from the neck 5026 is the shank upperportion 5008 that provides a connective or capture apparatus disposed ata distance from the upper end 5032 and thus at a distance from avertebra, such as the vertebra 13 when the body 5006 is implanted insuch vertebra.

The shank upper portion 5008 is configured for a pivotable connectionbetween the shank 5004 (with attached retainer 5012) and the receiver5010 prior to fixing of the shank 5004 in a desired position withrespect to the receiver 5010. The shank upper portion 5008 has an outer,convex and substantially spherical lower surface 5034 that extendsoutwardly and upwardly from the neck 5026 and terminates at an annularsurface 5036. The spherical lower surface 5034 has an outer radius thatis the same or substantially similar to an outer radius of the retainer5012, the surface 5034 as well as the retainer 5012 outer surfaceparticipating in the ball and socket joint formed by the shank 5004 andattached retainer 5012 within the partially spherical surface definingan inner cavity of the receiver 5010. Adjacent the surface 5034 is theannular, planar lower ledge surface 5036 positioned perpendicular to acentral axis of the shank 5004. Extending upwardly from the lower ledge5036 is a cylindrical surface 5038 formed about the shank central axis.Extending from the cylindrical surface 5038 is an annular surface orupper ledge 5040 that is opposite the lower ledge 5036, the upper ledge5040 also being substantially perpendicular to the central axis of theshank 5004. The cylindrical surface 5038 and the upper and lower ledges5036 and 5040 cooperate to capture and fix the resilient open retainer5012 to the shank upper portion 5008, prohibiting movement of theretainer 5012 along the shank axis once the retainer 5012 is locatedbetween the ledges 5036 and 5040. Extending upwardly from the upperledge 5040 is a spherical or domed surface 5044. The spherical surface5044 has an outer radius configured for sliding cooperation and ultimatefrictional mating with a substantially spherical concave surface of thecompression insert 5014 that has the same or substantially similarradius as the surface 5044. The radius of the surface 5044 is the sameor substantially the same as the radius of the lower spherical surface5034 and the outer radius of the retainer 5012. Located near or adjacentto the surface 5044 is an annular top surface 5046. A counter sunkinternal drive feature 5050 is formed in the top surface 5046 and has ahex shape designed to receive a hex tool (not shown) of an Allen wrenchtype, into the aperture for rotating and driving the bone screw shank5004.

The open retainer 5012 that operates to capture the shank upper portion5008 within the receiver 5010 is made from a resilient material, such asa stainless steel or titanium alloy, so that the retainer 5012 may beexpanded during assembly. However, because there is no need to compressthe retainer 5012 during assembly, an opening or slit, generally 5108that allows for expansion of the retainer 5012 is designed to be verynarrow, advantageously providing substantial or almost full surfacecontact between the retainer and the shank upper portion 5008 and alsobetween the retainer and the receiver 5010 seating surface. The retainer5012 has a central channel or hollow through bore that passes entirelythrough the structure 5012 from a top surface 5102 to a bottom surface5104 thereof. The bore is primarily defined by a discontinuous innercylindrical surface 5105 that runs from the top surface 5102 to thebottom surface 5104. The retainer 5012 further includes an outersubstantially spherical surface 5107 running between the top surface5102 and the bottom surface 5104, the surface 5107 having the same orsimilar radius (when in a neutral or near neutral state) as the receiver5010 seating surface and the shank lower spherical surface 5034 and thusthe same radius as the dome 5044 of the shank 5004 that engages theinsert 5014. The resilient retainer 5012 further includes first andsecond end surfaces disposed in spaced relation to one another formingthe slit 5108 when the retainer is in a neutral or near neutral state.

The assembly 5001 is assembled in a manner similar to the assembly 1,for example, as previously described herein, with the shank upperportion 5008 being snapped or popped into the receiver 5010 by pushingthe shank spherical surface 5044 through the retainer 5012 alreadylocated within the receiver inner cavity. As shown in FIG. 68, onceassembled, the cylindrical surface 5038 of the shank 5004 aligns andclosely contacts the cylindrical surface 5105 the retainer 5012 with theretainer bottom surface 5104 seated on the shank lower ledge surface5036 and the retainer top surface 5102 abutting against the shank upperledge surface 5040, providing a secure fit between the shank 5004 andthe retainer 5012, the retainer 5012 thus capturing the shank head 5008within the receiver 5010. Further assembly and disassembly, if desired,and implantation and operation of the assembly 5001 is performed in amanner identical to what has been described herein with respect to theassemblies 1, 201, 601 and 801, for example.

With reference to FIGS. 69-70 the reference number 6001 generallyrepresents a polyaxial bone screw apparatus or assembly according to thepresent invention. The assembly 6001 includes a shank 6004, that furtherincludes a body 6006 integral with an upwardly extending upper portionor capture structure 6008; a receiver 6010; an open retainer structure6012 and a compression or pressure insert 6014. FIGS. 69 and 70 furthershow a closure structure 6018 of the invention for capturing alongitudinal connecting member, for example, a rod 6021 within thereceiver 6010. The rod 6021 is the same or substantially similar to therod 21 or other longitudinal connecting members previously describedherein with respect to the assembly 1. The receiver 6010, the insert6014, the closure top 6018 and the rod 6021 are identical orsubstantially similar to the respective receiver 210, insert 214,closure top 218 and rod 221 previously described herein with respect tothe assembly 201 shown in FIGS. 21-29 and previously described herein.It is noted that the receiver 6010 has been slightly modified toaccommodate the retainer 6012 that is taller than the retainer 212. Theshank 6004 and the retainer 6012 are similar to the respective shank 204and retainer 212 of the assembly 201, but there are some differences.Primarily, the shank and retainer have been modified to have afrusto-conical interface as compared to the cylindrical interface shownbetween the shank 204 and the retainer 212. Furthermore, the shank andretainer have been modified to provide an assembly wherein the retainer6012 has an outer radius that is the same as an upper outer radius ofthe shank 6010 that in turn engages the insert 6014 at a lower concavesurface thereof, also having the same radius.

Specifically, the shank 6004, having the shank body 6006 includes ahelically wound bone implantable thread 6024 (single or dual lead threadform) extending from near a neck 6026 located adjacent to the upperportion or capture structure 6008, to a tip 6028 of the body 6006 andextending radially outwardly therefrom. The neck 6026 extends axiallyupward from the shank body 6006. The neck 6026 may be of the same or istypically of a slightly reduced radius as compared to an adjacent upperend or top 6032 of the body 6006 where the thread 6024 terminates.Further extending axially and outwardly from the neck 6026 is the shankupper portion 6008 that provides a connective or capture apparatusdisposed at a distance from the upper end 6032 and thus at a distancefrom a vertebra, such as the vertebra 13 when the body 6006 is implantedin such vertebra.

The shank upper portion 6008 is configured for a pivotable connectionbetween the shank 6004 (with attached retainer 6012) and the receiver6010 prior to fixing of the shank 6004 in a desired position withrespect to the receiver 6010. The shank upper portion 6008 has an outer,convex and substantially spherical lower surface 6034 that extendsoutwardly and upwardly from the neck 6026 and terminates at acylindrical surface 6036. The spherical lower surface 6034 has an outerradius that is the same or substantially similar to an outer radius ofthe retainer 6012 so that the surface 6034 as well as the retainer 6012outer surface participating in the ball and socket joint formed by theshank 004 and attached retainer 6012 within the partially sphericalsurface defining an inner cavity of the receiver 6010. However, in otherembodiments, the radius of the shank portion 6034 may be different thana radius of the retainer 6012. Adjacent the cylindrical surface 6036 isan upwardly and inwardly extending frusto-conical surface 6038.Extending outwardly from the frusto-conical surface 6038 is an annularsurface or upper ledge 6040 that faces downwardly toward thefrusto-conical surface 6038 and is substantially perpendicular to acentral axis of the shank 6004. The frusto-conical surface 6038 and theupper ledge 6040 cooperate to capture and fix the resilient openretainer 6012 to the shank upper portion 6008, prohibiting movement ofthe retainer 6012 along the shank axis once the retainer 6012 is locatedbeneath ledge 6040. The illustrated frusto-conical surface 6038 isnarrower at a top thereof. In other words, a diameter of the surface6038 near the upper ledge 6040 is smaller than a diameter of the surface6038 near the lower spherical surface 6034. Extending upwardly from theupper ledge 6040 is a cylindrical surface 6042 followed by a sphericalor domed surface 6044. The spherical surface 6044 has an outer radiusconfigured for sliding cooperation and ultimate frictional mating with asubstantially spherical concave surface of the compression insert 6014that has the same or substantially similar radius as the surface 6044.The radius of the surface 6044 is the same or substantially similar tothe radius of the lower spherical surface 6034 and the outer sphericalsurface of the retainer 6012. Located near or adjacent to the surface6044 is an annular top surface 6046. A counter sunk internal drivefeature 6050 is formed in the top surface 6046 and has a hex shapedesigned to receive a hex tool (not shown) of an Allen wrench type, intothe aperture for rotating and driving the bone screw shank 6004.

The open retainer 6012 that operates to capture the shank upper portion6008 within the receiver 6010 is made from a resilient material, such asa stainless steel or titanium alloy, so that the retainer 6012 may beexpanded during assembly. However, because there is no need to compressthe retainer 6012 during assembly, an opening or slit, generally 6108that allows for expansion of the retainer 6012 is designed to be verynarrow, advantageously providing substantial or almost full surfacecontact between the retainer and the shank upper portion 6008 and alsobetween the retainer and the receiver 6010 seating surface. The retainer6012 has a central channel or hollow through bore that passes entirelythrough the structure 6012 from a top surface 6102 to a bottom surface6104 thereof. The bore is primarily defined by a discontinuous innerfrusto-conical surface 6105 that runs from the top surface 6102 to thebottom surface 6104. The retainer 6012 further includes an outersubstantially spherical surface 6107 running between the top surface6102 and the bottom surface 6104, the surface 6107 having the same orsimilar radius (when the resilient retainer 6012 is in a non-expanded,neutral or near neutral state) as the receiver 6010 seating surface, theshank lower spherical surface 6034 and the dome 6044 of the shank 6004that engages the similarly radiused lower surface of the insert 6014.The resilient retainer 6012 further includes first and second endsurfaces disposed in spaced relation to one another forming the slit6108 when the retainer is in a neutral or near neutral state.

The assembly 6001 is assembled in a manner similar to the assembly 1,201 and 601, for example, as previously described herein, with the shankupper portion 6008 being snapped or popped into the receiver 6010 bypushing the shank spherical surface 6044 through the retainer 6012already located within the receiver inner cavity. As shown in FIG. 70,once assembled, the frusto-conical surface 6038 of the shank 6004closely contacts the frusto-conical surface 6105 of the retainer 6012along an entire surface thereof with a portion of the retainer topsurface 6102 abutting against the shank ledge surface 6040, providing asecure fit between the shank 6004 and the retainer 6012, the retainer6012 thus capturing the shank head 6008 within the receiver 6010.Further assembly and disassembly, if desired, and implantation andoperation of the assembly 6001 is performed in a manner identical towhat has been described herein with respect to the assemblies 1, 201,601 and 801, for example.

With reference to FIGS. 71-72 the reference number 7001 generallyrepresents a polyaxial bone screw apparatus or assembly according to thepresent invention. The assembly 7001 includes a shank 7004, that furtherincludes a body 7006 integral with an upwardly extending upper portionor capture structure 7008; a receiver 7010; an open retainer structure7012 and a compression or pressure insert 7014. FIGS. 71 and 72 furthershow a closure structure 7018 of the invention for capturing alongitudinal connecting member, for example, a rod 7021 within thereceiver 7010. The rod 7021 is the same or substantially similar to therod 21 or other longitudinal connecting members previously describedherein with respect to the assembly 1. The receiver 7010, the insert7014, the closure top 7018 and the rod 7021 are identical orsubstantially similar to the respective receiver 210, insert 214,closure top 218 and rod 221 previously described herein with respect tothe assembly 201 shown in FIGS. 21-29. It is noted that the receiver7010 has been slightly modified to accommodate the retainer 7012 that istaller than the retainer 212. The shank 7004 and the retainer 7012 aresimilar to the respective shank 204 and retainer 212 of the assembly201, but there are some differences. Primarily, the shank and retainerhave been modified to have a combination frusto-conical and cylindricalinterface as compared to the cylindrical interface shown between theshank 204 and the retainer 212. Furthermore, the shank and retainer havebeen modified to provide an assembly wherein the retainer 7012 has anouter radius that is the same as an upper outer radius of the shank 7010that in turn engages the insert 7014 at a lower concave surface thereof,also having the same radius.

Specifically, the shank 7004, having the shank body 7006 includes ahelically wound bone implantable thread 7024 (single or dual lead threadform) extending from near a neck 7026 located adjacent to the upperportion or capture structure 7008, to a tip 7028 of the body 7006 andextending radially outwardly therefrom. The neck 7026 extends axiallyupward from the shank body 7006. The neck 7026 may be of the same orslightly reduced radius as compared to an adjacent upper end or top 7032of the body 7006 where the thread 7024 terminates. Further extendingaxially and outwardly from the neck 7026 is the shank upper portion 7008that provides a connective or capture apparatus disposed at a distancefrom the upper end 7032 and thus at a distance from a vertebra, such asthe vertebra 13 when the body 7006 is implanted in such vertebra.

The shank upper portion 7008 is configured for a pivotable connectionbetween the shank 7004 (with attached retainer 7012) and the receiver7010 prior to fixing of the shank 7004 in a desired position withrespect to the receiver 7010. The shank upper portion 7008 has an outer,convex and substantially spherical lower surface 7034 that extendsoutwardly and upwardly from the neck 7026 and terminates at acylindrical surface 7035. The spherical lower surface 7034 has an outerradius that is the same or substantially similar to an outer radius ofthe retainer 7012 so that the surface 7034 as well as the retainer 7012outer surface participating in the ball and socket joint formed by theshank 7004 and attached retainer 7012 within the partially sphericalsurface defining an inner cavity of the receiver 7010. However, in otherembodiments, the radius of the shank portion 7034 may be different thana radius of the retainer 7012. Adjacent the cylindrical surface 7035 isan annular surface 7036 disposed perpendicular to a central axis of theshank 7004. The surface 7036 is in turn adjacent to an upwardly andinwardly extending frusto-conical surface 7038. Extending outwardly fromthe frusto-conical surface 7038 is an annular surface or upper ledge7040 that faces downwardly toward the frusto-conical surface 7038 and issubstantially perpendicular to the central axis of the shank 7004. Thecylindrical surface 7035, lower ledge 7036, frusto-conical surface 7038and upper ledge 7040 cooperate to capture and fix the resilient openretainer 7012 to the shank upper portion 7008, prohibiting movement ofthe retainer 7012 along the shank axis once the retainer 7012 is locatedbeneath ledge 7040. The illustrated frusto-conical surface 7038 isnarrower at a top thereof. In other words, a diameter of the surface7038 near the upper ledge 7040 is smaller than a diameter of the surface7038 near the cylindrical surface 7035. Extending upwardly from theupper ledge 7040 is a cylindrical surface 7042 followed by a sphericalor domed surface 7044. The spherical surface 7044 has an outer radiusconfigured for sliding cooperation and ultimate frictional mating with asubstantially spherical concave surface of the compression insert 7014that has the same or substantially similar radius as the surface 7044.The radius of the surface 7044 is the same or substantially similar tothe radius of the lower spherical surface 7034 and the outer sphericalsurface of the retainer 7012. Located near or adjacent to the surface7044 is an annular top surface 7046. A counter sunk internal drivefeature 7050 is formed in the top surface 7046 and has a hex shapedesigned to receive a hex tool (not shown) of an Allen wrench type, intothe aperture for rotating and driving the bone screw shank 7004.

The open retainer 7012 that operates to capture the shank upper portion7008 within the receiver 7010 is made from a resilient material, such asa stainless steel or titanium alloy, so that the retainer 7012 may beexpanded during assembly. However, because there is no need to compressthe retainer 7012 during assembly, an opening or slit, generally 7108that allows for expansion of the retainer 7012 is designed to be verynarrow, advantageously providing substantial or almost full surfacecontact between the retainer and the shank upper portion 7008 and alsobetween the retainer and the receiver 7010 seating surface. The retainer7012 has a central channel or hollow through bore that passes entirelythrough the structure 7012 from a top surface 7102 to a bottom surface7104 thereof. The bore is primarily defined by a discontinuous innerfrusto-conical surface 7105 that runs from the top surface 7102 to acylindrical surface 7106 that in turn is adjacent to the bottom surface7104. The retainer 7012 further includes an outer substantiallyspherical surface 7107 running between the top surface 7102 and thebottom surface 7104, the surface 7107 having the same or similar radius(when the resilient retainer 7012 is in a non-expanded, neutral or nearneutral state) as the receiver 7010 seating surface, the shank lowerspherical surface 7034 and the dome 7044 of the shank 7004 that engagesthe similarly radiused lower surface of the insert 7014. The resilientretainer 7012 further includes first and second end surfaces disposed inspaced relation to one another forming the slit 7108 when the retaineris in a neutral or near neutral state.

The assembly 7001 is assembled in a manner similar to the assembly 1,201 and 601, for example, as previously described herein, with the shankupper portion 7008 being snapped or popped into the receiver 7010 bypushing the shank spherical surface 7044 through the retainer 7012already located within the receiver inner cavity. As shown in FIG. 72,once assembled, the frusto-conical surface 7038 of the shank 7004closely contacts the frusto-conical surface 7105 of the retainer 7012along an entire surface thereof with a portion of the retainer topsurface 7102 abutting against the shank ledge surface 7040. Also, theretainer inner cylindrical surface 7106 closely mates with the shankouter cylindrical surface 7035, with a portion of the retainer beingseated on the ledge surface 7036. Such a plurality of closely contactingsurfaces provides a secure fit between the shank 7004 and the retainer7012, the retainer 7012 thus capturing the shank head 7008 within thereceiver 7010. Further assembly and disassembly, if desired, andimplantation and operation of the assembly 7001 is performed in a manneridentical to what has been described herein with respect to theassemblies 1, 201, 601 and 801, for example.

It is to be understood that while certain forms of the present inventionhave been illustrated and described herein, it is not to be limited tothe specific forms or arrangement of parts described and shown.

What is claimed is:
 1. A pivotal bone anchor assembly for securing anelongate rod to a bone of a patient via a closure, the pivotal boneanchor assembly comprising: a shank comprising a longitudinal axis, acapture structure at a proximal end, and an anchor portion opposite thecapture structure configured for attachment to the bone, the capturestructure including a circumferential capture recess centered on thelongitudinal axis with a first radiused surface above the capture recessand a second radiused surface below the capture recess, the capturerecess being defined by at least an upper ledge and an outwardly-facingrecessed surface extending downward from the upper ledge; a receivercomprising a vertical centerline axis, a base portion defining an axialbore centered around the vertical centerline axis, and an upper portiondefining a channel configured to receive a portion of the elongate rod,the axial bore communicating with a bottom of the receiver through abottom opening and extending upward through the channel to a top of thereceiver, the axial bore having a lower portion configured to receivethe capture structure of the shank including a partially sphericalseating surface adjacent the bottom opening and an expansion chamberlocated above the seating surface having a downward-facing at leastpartially annular stop surface integrally formed therein; and aresilient retainer positionable within the lower portion of the axialbore prior to the capture structure of the shank, the retainer having anupper surface, a lower surface, an outwardly-facing third radiusedsurface extending between the upper and lower surfaces, and aninwardly-facing inner retainer surface complimentary with the recessedsurface of the capture recess, wherein upon the capture structure beinguploaded into the lower portion of the axial bore through the bottomopening, the upper surface of the retainer is configured engage the stopsurface of the expansion chamber and the inner retainer surface isconfigured to downwardly slidably engage the first radiused surface ofthe capture structure to cause the retainer to expand within theexpansion chamber, until the retainer slides over and off the firstradiused surface and snaps into the capture recess so as to couple theretainer to the capture structure and to align third radiused surfacewith the second radiused surface to form a partially spherical bearingsurface configured to pivotably engage the seating surface of the axialbore.
 2. The pivotal bone anchor assembly of claim 1, wherein the innerretainer surface has a nominal diameter that is substantially equal to anominal diameter of the recessed surface of the capture recess when theretainer in a neutral state.
 3. The pivotal bone anchor assembly ofclaim 2, wherein when the retainer is snapped into the capture recess,the retainer is in its neutral state with the inner retainer surfacecontacting the recess interface surface so that the resilient retaineris not compressible beyond its neutral state within the capture recess.4. The pivotal bone anchor assembly of claim 1, wherein the capturerecess is defined by the upper ledge, a lower ledge, and theoutwardly-facing recessed surface extending between the upper and lowerledges.
 5. The pivotal bone anchor assembly of claim 4, wherein when theretainer is snapped into the capture recess, the upper and lowersurfaces of the retainer are configured to slidably engage the upper andlower ledges of the capture recess, respectively.
 6. The pivotal boneanchor assembly of claim 4, wherein the recessed surface is cylindricalwith a constant diameter between the upper and lower ledges.
 7. Thepivotal bone anchor assembly of claim 4, wherein the recessed surface isfrusto-conical with a narrower diameter near the upper ledge and a widerdiameter near the lower ledge.
 8. The pivotal bone anchor assembly ofclaim 1, wherein the recessed surface is curvate with a varying diameteracross a width thereof.
 9. The pivotal bone anchor assembly of claim 1,wherein the retainer is a discontinuous open ring having a slit formedentirely through a thickness thereof between the upper surface and thelower surface.
 10. The pivotal bone anchor assembly of claim 1, whereinthe at least partially annular stop surface of the axial bore furthercomprises a bottom surface of an inwardly-protruding structure having adiameter less than an outer diameter of the upper surface of theretainer when the retainer is in the neutral state.
 11. The pivotal boneanchor assembly of claim 1, further comprising an insert positionableinto the axial bore of the receiver above the resilient retainer andconfigured to engage the first radiused surface of the capture structure12. The pivotal bone anchor assembly of claim 11, wherein the insert isconfigured to be positioned within the axial bore together with theretainer prior to the capture structure of the shank.
 13. The pivotalbone anchor assembly of claim 11, wherein the first and second radiusedsurfaces of the capture structure and the third radiused surface of theretainer are configured to align to define a partially spherical bearingsurface configured to pivotably engage both the seating surface and apartially spherical bottom surface of the insert.
 14. The pivotal boneanchor assembly of claim 12, wherein the partially spherical bottomsurface of the insert is configured to pivotally engage both the firstradiused surface and the third radiused surface.
 15. The pivotal boneanchor assembly of claim 11, wherein the insert includes a secondchannel sized and shaped for receiving the portion of the elongate rod,and wherein the insert is configured for top loading into the receiverand rotation about the receiver vertical centerline axis into positionabove the retainer after the retainer is positioned in the lower portionof the axial bore, with the second channel being rotatable intoalignment with the first channel.
 16. The pivotal bone anchor assemblyof claim 15, wherein at least one of the insert and the receiverincludes a rotation blocking feature configured to inhibit furtherrotation of the insert within the axial bore upon the second channelbecoming aligned with the first channel.
 17. The pivotal bone anchorassembly of claim 11, wherein the insert includes a second channel sizedand shaped for receiving the portion of the elongate rod, and whereinthe receiver has at least one of a crimped wall surface and a spring tabengageable with an exterior side surface of the insert to maintain thesecond channel in alignment with the first channel.